DCA

Question 1

What are the components of Docker Engine?

• REST API, Docker Daemon
• Images, Containers, Volumes
• Docker CLI, Docker Daemon, REST API

Answer 1

Docker CLI, Docker Daemon, REST API

Question 2

What component of the docker engine manages the images, containers, volumes, and networks on a host?

• REST API
• Docker Daemon
• Docker CLI

Answer 2

Docker Daemon

Question 3

What component of the Docker architecture is responsible for managing containers on Linux on version 1.15 of Docker Engine?

• LibContainer
• Docker API
• LXC

Answer 3

LibContainer

Question 4

We can run containers without installing Docker?

• True
• False

Answer 4

True

Question 5

Which component is responsible for keeping the containers alive when the Docker Daemon goes down?

• LibContainer
• Runc
• Containerd
• Containerd-Shim

Answer 5

Containerd-Shim

Question 6

What are the primary objects that Docker engine manages?

• RunC
• LibContainer
• Images, Containers, Volumes, Networks

Answer 6

• Images, Containers, Volumes, Networks

Question 7

By default, data stored inside the container is always persistent?

• True
• False

Answer 7

False

Question 8

By default, Docker is configured to look for images on Google Cloud Registry?

• True
• False

Answer 8

False

Question 9

Which component is a read-only template used for creating a Docker container?

• Docker Network
• Docker Images
• Container
• Docker volume

Answer 9

Docker Images

Question 10

What is the default data directory for Docker?

• /var/lib/docker
• /var/log/docker
• /etc/docker
• /home/docker

Answer 10

/var/lib/docker

Question 11

What does OCI stand for?

• Open Communication Initiative
• Open Container Initiative
• Open Command Interface
• Open Container Interface

Answer 11

Open Container Initiative

Question 12

What are the 2 specifications from OCI?

• container-spec
• runtime-spec
• image-spec
• oci-spec
• libcontainer-spec

Answer 12

• runtime-spec

- image-spec

Question 13

What is the command to view the version of docker engine installed?

• docker –version
• docker version
• docker engine info
• docker info engine

Answer 13

docker version

Question 14

What is the command to start docker daemon manually?

• docker
• dockerd
• docker-engine
• docker –start-engine

Answer 14

dockerd

Question 15

On what interfaces are the docker daemon made available by default?

• TCP socket
• UDP socket
• Unix socket
• 192.168.1.10

Answer 15

Unix Socket

Question 16

What is the port conventionally used to configure un-encrypted traffic on TCP?

• 2345
• 2346
• 2375
• 2376

Answer 16

2375

Question 17

What file is used to configure the docker daemon?

• /var/lib/docker/docker.conf
• /var/lib/docker/daemon.json
• /etc/docker/daemon.json
• /etc/docker/daemon.conf

Answer 17

• /etc/docker/daemon.json

Question 18

What flags are used to configure encryption on docker daemon?

• tlsverify, tlscert, tlskey
• tlsverify, key, cert
• key, cert, tls
• host, key, cert, tls

Answer 18

tlsverify, tlscert, tlskey

Question 19

What is the default network driver used when a container is created?

• overlay
• bridge
• none
• host

Answer 19

bridge

Question 20

What is the command used to list the running containers on the Docker Host?

• docker container ls
• docker container start
• docker container stop
• None of the above

Answer 20

docker container ls

Question 21

Which of the below commands create a container with nginx image and name nginx?

• docker container create nginx –name nginx
• docker container –name nginx nginx
• docker container run nginx
• docker container create –name nginx nginx

Answer 21

docker container create –name nginx nginx

Question 22

How to list all running and stopped containers and their status?

• docker container ls
• docker container ls -a
• docker container ls -aq
• docker container ls -q

Answer 22

docker container ls -a

Question 23

How to start a stopped Container?

Answer 23

docker container start nginx

Question 24

How do I get only the IDs of running containers?

Answer 24

docker container ls -q

Question 25

What is the option used in docker run command to attach to the terminal of the container in an interactive mode?

Answer 25

-it

Question 26

What is the command to change the container name “httpd” to “webapp”?

• docker container rename httpd webapp
• docker container rename webapp httpd
• docker container replace –name httpd webapp
• docker container create –name webapp httpd

Answer 26

docker container rename httpd webapp

Question 27

What is the command to run a “nginx” container in a detached mode with name “webapp”?

• docker container run -it –name webapp nginx
• docker container run -it –name nginx webapp
• docker container run -d –name webapp nginx
• docker container run -d –name nginx webapp

Answer 27

docker container run -d –name webapp nginx

Question 28

You cannot start a killed container?

• True
• False

Answer 28

False

Question 29

Delete the stopped container named “webapp”.

• docker container delete webapp
• docker container remove webapp
• docker container kill webapp
• docker container rm webapp

Answer 29

docker container rm webapp

Question 30

Run a container called webapp with image nginx, and in an interactive mode.

• docker container run -it nginx
• docker container run -it nginx –name webapp
• docker container run nginx
• docker container run -it –name webapp nginx

Answer 30

• docker container run -it –name webapp nginx

Question 31

Which combination of keys are used to escape from the shell and keep the container webapp running?

• Ctrl + c
• Ctrl+p+q
• exit, Ctrl+p+q
• Ctrl+c,exit

Answer 31

Ctrl+p+q

Question 32

Which combination of keys are used to exit from the shell and stop the container webapp?

• Ctrl+c
• Ctrl+p+q
• Ctrl+p
• Ctrl+z

Answer 32

Ctrl+c

Question 33

You have a running container and want to execute a command inside it. Which command will you use?

• execute
• run
• start
• exec

Answer 33

exec

Question 34

We deployed a container called webapp. Inspect this container to get the IPPrefixLen

• docker container inspect webapp | grep IPPrefixLen
• docker container top webapp | grep IPPrefixLen
• docker container run webapp | grep IPPrefixLen
• docker container logs webapp | grep IPPrefixLen

Answer 34

docker container inspect webapp | grep IPPrefixLen

Question 35

We have deployed some containers. What command is used to get the container with the highest memory?

• docker container stats
• docker container status
• docker container top
• docker container ls

Answer 35

docker container stats

Question 36

How to display the running processes inside the container?

• docker container top container-name
• docker container stats container-name
• docker ps container-name
• docker container logs container-name

Answer 36

docker container top container-name

Question 37

You have a webapp container and image httpd.
Inspect the logs of the webapp container.
Which command is used to get the stream logs of the webapp container so that you can view the logs live?

Answer 37

docker container logs -f webapp

Question 38

Which command returns only new and/or live events?

• docker system info
• docker container events
• docker container events -f
• docker system events

Answer 38

docker system events

Question 39

Which command returns events since the paste 30 minutes?

• docker system events since 30m
• docker system events –since 30m
• docker container events –since 30m
• docker container events since 30m

Answer 39

docker system events –since 30m

Question 40

Which command is used to get the events of the container named “webapp”? (This one is for you to read the documentation)

• docker system events since 10m
• docker system events –filter ‘container=webapp’
• docker system events –filter ‘image=webapp’

Answer 40

docker system events –filter ‘container=webapp’

Question 41

Run a container named webapp with nginx image in detached mode. Select the right answer.

• docker container run –detach –name=webapp nginx
• docker container run –detach –name=nginx webapp
• docker container create -d –name=nginx webapp
• docker container create -d nginx

Answer 41

docker container run –detach –name=webapp nginx

Question 42

Stop the container named “nginx”

• docker container halt nginx
• docker container stop nginx
• docker container rm nginx
• docker container pause nginx

Answer 42

docker stop container nginx

Question 43

How do you list running & stopped containers?

• docker container ls -a
• docker container ls -q
• docker container ls
• docker container ls -q, docker container ls

Answer 43

docker container ls -a

Question 44

Delete the “webapp” Container. Select the right answer.

• docker container delete webapp
• docker container remove webapp
• docker container kill webapp
• docker container rm webapp

Answer 44

docker container rm webapp

Question 45

Stop all running containers on the host. Select the right answer.

• docker container stop $(docker container ls -a)
• docker container rm $(docker container ls -q)
• docker container stop $(docker container ls -q)
• docker container stop –all

Answer 45

docker container stop $(docker container ls -q)

Question 46

Delete all running and stopped containers on the host. (Explore the documentation to identify an option to force remove running containers)

• docker container stop $(docker container ls -q)
• docker container rm $(docker container ls -q)
• docker container stop $(docker container ps -q)
• docker container rm -f $(docker container ls -aq)

Answer 46

docker container rm -f $(docker container ls -aq)

Question 47

Which command is used to delete the stopped containers?

• docker container remove $(docker container ls -aq)
• docker container rm $(docker container ls -aq)
• docker container prune
• docker container rm –all

Answer 47

docker container prune

Question 48

What is the command to pause a running container?

• docker container pause
• docker container –pause
• docker container halt
• docker container SIGSTOP

Answer 48

docker container pause

Question 49

What are the signals sent to a running container when the docker container stop command is executed?

• SIGSTOP followed by SIGKILL
• SIGTERM followed by SIGKILL
• SIGKILL followed by SIGTERM
• SIGKILL followed by SIGSTOP

Answer 49

SIGTERM followed by SIGKILL

Question 50

Run a container with image nignx, name nginx and hostname webapp.

• docker container run -d –name webapp –hostname=webapp nginx
• docker container run -d –name nginx webapp
• docker container run -d –name nginx –hostname=webapp nginx
• docker container run -d –name webapp nginx

Answer 50

docker container run -d –name nginx –hostname=webapp nginx

Question 51

What is the hostname set on the container when the following command is run: docker container run -d –name webapp httpd

• webapp
• apache
• httpd
• containers unique id

Answer 51

containers unique id

Question 52

What is the default restart policy?

• unless-stopped
• on-failure
• no
• always

Answer 52

no

Question 53

Which policy would restart the containers even after the docker daemon is restarted?

• unless-stopped
• on-failure
• always
• always, unless-stopped

Answer 53

always

Question 54

Which policy is used to restart a container unless it is explicitly stopped or Docker is restarted?

• unless-stopped
• on-failure
• no
• always

Answer 54

unless-stopped

Question 55

Which command can be used to check the restart policy of webapp container?

• docker container inspect webapp
• docker container info webapp
• docker container check webapp
• None of above

Answer 55

docker container inspect webapp

Question 56

Restart container unless it is explicitly stopped or Docker is restarted.

• unless-stopped
• on-failure
• no
• always

Answer 56

unless-stopped

Question 57

Which command should be used to update the httpd container with the always policy?

• docker container update –restart always httpd
• docker container unpause –restart always httpd
• docker container upgrade –restart always httpd

Answer 57

docker container update –restart always httpd

Question 58

Which command should be used to update all the running containers with unless-stopped policy?

• docker container upgrade –restart unless-stopped $(docker container ls -q)
• docker container update –restart unless-stopped $(docker container ls -q)
• docker container upgrade –restart unless-stopped $(docker container ls -aq)
• docker container update –restart unless-stopped $(docker container ls -aq)

Answer 58

docker container update –restart unless-stopped $(docker container ls -q)

Question 59

Which option is used to reduce container downtime due to daemon crashes, planned outages, or upgrades?

• Restart Policy
• Swarm
• LIve Rest

Answer 59

Live Restore

Question 60

What is the path file which is used to add the live restore?

• /etc/docker/daemon.json
• /var/lib/docker/daemon.json
• /var/log/docker/daemon.json
• /var/lib/docker

Answer 60

/etc/docker/daemon.json

Question 61

How to enable the live restore setting to keep containers alive when the daemon becomes unavailable?

• echo ‘{“live-restore”: true}’&raquo_space; /etc/docker/daemon.json
• echo ‘{“live-restore”: true}’&raquo_space; /var/lib/docker/daemon.json
• echo ‘{true: “live-restore”}’&raquo_space; /etc/docker/daemon.json
• echo ‘{true: “live-restore”}’&raquo_space; /var/lib/docker/daemon.json

Answer 61

echo ‘{“live-restore”: true}’&raquo_space; /etc/docker/daemon.json

Question 62

Which of the below commands may be used to copy a file /web.conf from a container named webapp with id 89683681 to the /tmp directory on the host?

• docker container cp /tmp/web.conf webapp:/etc/web.conf
• docker container cp webapp:/web.conf /webapp
• docker container cp 89683681:/web.conf /tmp/
• docker container cp webapp:/web.conf /tmp/

Answer 62

docker container cp webapp:/web.conf /tmp/

Question 63

Copy the /etc/nginx directory from the webapp container to the docker host under /tmp/.

• docker container copy webapp:/etc/nginx /tmp/
• docker container cp webapp:/etc/nginx /tmp/
• docker container copy /tmp/ webapp:/etc/nginx
• docker container cp /tmp/ webapp:/etc/nginx

Answer 63

docker container cp webapp:/etc/nginx /tmp/

Question 64

What is the command to copy the file /root/myfile.txt from the host to /root/ of the webapp container?

• docker container copy /root/myfile.txt webapp:/root/
• docker container cp /root/myfile.txt webapp:/root/
• docker container copy webapp:/root/ /root/myfile.txt
• docker container cp webapp:/root/ /root/myfile.txt

Answer 64

docker container cp /root/myfile.txt webapp:/root/

Question 65

We can copy a file from a stopped container?

• True
• False

Answer 65

True

Question 66

Data inside a container is persistent?
True
False

Answer 66

False

Question 67

You can run multiple instances of the same application on the docker host?

True
False

Answer 67

True

Question 68

You can map the same port on the Docker host more than once?

Answer 68

False

Question 69

Which option could be used to expose a webapp container to the outside world?

• p
• P
• -publish
• -expose

Answer 69

• p
• P
• -publish

Question 70

Map TCP port 80 in the container to port 8080 on the Docker host for connections to host IP 192.168.1.10 . Select the all right answers

• p 192.168.1.10:8080:80
• p 192.168.1.10:80:8080
• p 192.168.1.10:8080:80/tcp
• p 192.168.1.10:8080:8080

Answer 70

-p 192.168.1.10:8080:80

Question 71

Unless specified otherwise, docker publishes the exposed port on all network interfaces.

• True
• False

Answer 71

True

Question 72

Map UDP port 80 in the container to port 8080 on the Docker host.

-p 8080:80/udp
-p 80:8080/udp
-P 8080:80/udp
None of the above

Answer 72

-p 8080:80/udp

Question 73

How does the -P option in the docker container run command know what ports to publish on the container?

• It identifies the ports listening inside the container using netstat command
• It uses the ExposedPorts field set on the container or the EXPOSE instruction in the Dockerfile
• It requires the –expose command line argument
• It assigns random ports between 32768 and 61000

Answer 73

It uses the ExposedPorts field set on the container or the EXPOSE instruction in the Dockerfile

Question 74

How does docker map a port on a container to a port on the host?

• Using an internal load balancer
• FirewallD Rules
• Using an external load balancer
• IPTables Rules

Answer 74

IPTables Rules

Question 75

What IPTables chains does Docker modify to configure port mapping on a host?

• INPUT
• FORWARD
• DOCKER
• OUTPUT

Answer 75

DOCKER

Question 76

How to check the logs of the docker daemon?

• journalctl -u docker.service
• less /var/log/messages
• less /var/log/daemon.log
• /var/log/docker.log

Answer 76

journalctl -u docker.service
less /var/log/messages
less /var/log/daemon.log
/var/log/docker.log

Question 77

Enable the debugging mode. Select the right answer

• echo ‘{“debug”: true}’ > /etc/docker/daemon.json
• echo ‘{“debug”}’ > /etc/docker/daemon.json
• echo ‘{“debug”: true}’ > /var/lib/docker/daemon.json
• echo ‘{“debug”}’ > /var/lib/docker/daemon.json

Answer 77

echo ‘{“debug”: true}’ > /etc/docker/daemon.json

Question 78

How to check if the docker service is running or not?

• docker status
• sudo systemctl status docker
• sudo systemctl docker status
• sudo service status docker

Answer 78

sudo systemctl status docker

Question 79

Which environment variable will be used to connect a remote docker server?

• DOCKER_REMOTE
• DOCKER_HOST
• DOCKER_CONFIG
  None of the above

Answer 79

DOCKER_HOST

Question 80

What may be the cause of this error: “unable to configure the Docker daemon with file /etc/docker/daemon.json: the following directives are specified both as a flag and in the configuration file: tls: (from flag: true, from file: false)”?

The tls flag is set to true in daemon.json file and false in the command line

The tls flag is set to false in daemon.json file and true in the command line

The tls flag is not set on the command line

The tls flag is not set in the daemon.json file

Answer 80

The tls flag is set to false in daemon.json file and true in the command line

Question 81

What is the default logging driver?

json-file
syslog
journald
splunk

Answer 81

json-file

Question 82

Where is the log of the webapp container with id 78373635 on the Docker Host?

/var/lib/docker/containers/78373635/78373635.json
/var/log/docker/78373635.json
/etc/docker/78373635.json
/var/lib/docker/tmp/78373635/78373635.json

Answer 82

/var/lib/docker/containers/78373635/78373635.json

Question 83

Which command is used to check the default logging driver?

docker system df
docker system events
docker system prune
docker system info

Answer 83

docker system info

Question 84

How to change the default logging driver to syslog?

echo ‘{“log-driver”: “syslog”}’ > /etc/docker/daemon.json

echo ‘{“syslog”: “log-driver”}’ > /etc/docker/daemon.json

echo ‘{“log-driver”: “syslog”}’ > /var/lib/docker/daemon.json

echo ‘{“syslog”: “log-driver”}’ > /var/lib/docker/daemon.json

Answer 84

echo ‘{“log-driver”: “syslog”}’ > /etc/docker/daemon.json

Question 85

Run a webapp container, and make sure that no logs are configured for this container.

docker run -it –log-driver none webapp
docker run -it –logging-driver none webapp
docker run -it webapp
docker run -it –log none webapp

Answer 85

docker run -it –log-driver none webapp

Question 86

Which of the below commands create a container with redis image and name redis?

docker container create redis –name redis
docker container –name redis redis
docker container run redis
docker container create –name redis redis

Answer 86

docker container create –name redis redis

Question 87

We have deployed some containers. What command is used to get the container with the highest memory?

docker container stats
docker container status
docker container top
docker container ls

Answer 87

docker container stats

Question 88

Run a container called apps with image nginx, and in an interactive mode.

docker container run -it nginx
docker container run -it nginx –name apps
docker container run nginx
docker container run -it –name apps nginx

Answer 88

docker container run -it –name apps nginx

Question 89

You can run multiple instances of the same application on the docker host.

True
False

Answer 89

True

Question 90

Which of the below commands create a container with redis image and name redis?

docker container create redis –name redis
docker container –name redis redis
docker container run redis
docker container create –name redis redis

Answer 90

docker container create –name redis redis

Question 91

Which command should be used to update the restart policy of the httpd container with always?

docker container update –restart always httpd
docker container unpause –restart always httpd
docker container upgrade –restart always httpd
None of the above

Answer 91

docker container update –restart always httpd

Question 92

You can map multiple containers to the same port on the Docker host.

True
False

Answer 92

False

Question 93

Which command is used to check the default logging driver?

docker system df
docker system events
docker system prune
docker system info

Answer 93

docker system info

Question 94

What is the command to copy the file /root/myconfig.txt from the host to /root/ of the data container?

docker container copy /root/myconfig.txt data:/root/
docker container cp /root/myconfig.txt data:/root/
docker container copy data:/root/ /root/myconfig.txt
docker container cp data:/root/ /root/myconfig.txt

Answer 94

docker container cp /root/myconfig.txt data:/root/

Question 95

Which command is used to update all running containers with the <code>unless-stopped</code> restart policy?

docker container upgrade –restart unless-stopped $(docker container ls -q)
docker container update –restart unless-stopped $(docker container ls -q)
docker container upgrade –restart unless-stopped $(docker container ls -aq)
docker container update –restart unless-stopped $(docker container ls -aq)

Answer 95

docker container update –restart unless-stopped $(docker container ls -aq)

Question 96

What is the purpose of a private registry?

tightly control where your images are being stored

fully own your images distribution pipeline

integrate image storage and distribution tightly into your in-house development workflow

All of the above

Answer 96

All of the above

Question 97

What is the default public registry for docker?

Docker Hub
Amazon Container Registry
Google Container Registry
Docker Trusted Registry

Answer 97

Docker Hub

Question 98

What is the default tag if not specified when building an image with the name webapp?

none
default
latest
v1

Answer 98

latest

Question 99

Run ubuntu container with the trusty tag.

docker run ubuntu
docker run ubuntu:latest
docker run ubuntu:trusty
docker run ubuntu -t trusty

Answer 99

docker run ubuntu:trusty

Question 100

Select the right answer. Which command is used to list the local images?

docker image ls
docker images ls
docker container image ls
docker container images ls

Answer 100

docker image ls

Question 101

List the full length image IDs. (Please explore documentation)

docker image ls –digests
docker images –digests
docker images –no-trunc
None of the above

Answer 101

docker images –no-trunc

Question 102

Display images with a name containing postgres, at least 12 stars.

docker find –filter=stars=12 postgres
docker search –filter=stars=12 postgres
docker find –limit=12 postgres
docker search –limit=12 postgres

Answer 102

docker search –filter=stars=12 postgres

Question 103

Download nginx image from the Google Container Registry hub registry.

docker image pull nginx
docker image build nginx
docker image load nginx
docker pull gcr.io/kodekloud/nginx

Answer 103

docker pull gcr.io/kodekloud/nginx

Question 104

Display images with a name containing busybox, at least 3 stars and are official builds.

docker find –filter is-official=true –filter stars=3 busybox
docker search –filter is-official=true –filter stars=3 busybox
docker find –filter is-official=true –limit=3 busybox
docker search –filter is-official=true –limit=3 busybox

Answer 104

docker search –filter is-official=true –filter stars=3 busybox

Question 105

What is the command to change the tag of “httpd:latest” to “httpd:v1” ?

docker container image retag httpd:latest httpd:v1
docker container image tag httpd:latest httpd:v1
docker image retag httpd:latest httpd:v1
docker image tag httpd:latest httpd:v1

Answer 105

docker image tag httpd:latest httpd:v1

Question 106

You have an nginx:v1 image with size 100M. You’ve now created your own version of the image – nginx:v2 by retagging the first image, what is the total size of both?

50M
100M
150M
200M

Answer 106

100M

Question 107

Which command should be used to get the total size consumed by all images on a host?

docker image list
docker image df
docker system df
docker system list

Answer 107

docker system df

Question 108

In the output of the “docker system df” command what does the ACTIVE field indicate on the images row?

Number of Images currently available on the system
Number of Images built on the system
Number of Images with containers
Number of containers running on the system

Answer 108

Number of Images with containers

Question 109

What command might have generated the above output?

docker container ps
docker ps
docker image ps
docker image list

Answer 109

docker image list

Question 110

Inspect the following output and answer the following questions:

REPOSITORY TAG IMAGE ID CREATED SIZE
nginx latest c39a868aad02 4 days ago 150MB
redis latest 4760dc956b2d 2 years ago 100MB
ubuntu trusty f975c5035748 2 years ago 100MB
webapp latest c39a868aad02 4 days ago 150MB
alpine latest 3fd9065eaf02 2 years ago 5MB

What is the total space consumed by images on this system?

355 MB
505 MB
405 MB
455 MB

Answer 110

355 MB

Question 111

When you run the docker image inspect ubuntu command it gives the error “No such image”. Why is that?

Must run the command docker inspect ubuntu/ubuntu
Image Ubuntu does not have the latest tag
Must authenticate to docker hub first before running this command
Must run the command docker image history ubuntu

Answer 111

Image Ubuntu does not have the latest tag

Question 112

What is the user/account and image/repository name for the image company/nginx?

image=company, user=nginx
image=company, user=company
image=nginx, user=nginx
image=nginx, user=company

Answer 112

image=nginx, user=company

Question 113

Choose the right command to pull ubuntu image from a private registry at gcr.io

docker pull ubuntu
docker pull kk/ubuntu
docker pull gcr.io/kk/ubuntu
All of the above

Answer 113

docker pull gcr.io/kk/ubuntu

Question 114

Which command is used to authenticate with azr.com registry which listens on port 5000?

docker auth azr.com:5000
docker login azr.com:5000

Answer 114

docker login azr.com:5000

Question 115

You are required to store a copy of the official alpine image in your company’s internal docker registry. What would be your approach?

Create a Dockerfile similar to the official image and build an image
Pull the official image, tag it with the address of the internal docker registry and push to the internal docker registry

Answer 115

Pull the official image, tag it with the address of the internal docker registry and push to the internal docker registry

Question 116

When you log in to a registry, the command stores credentials in … (Please explore the documentation pages for this)

$HOME/.docker/config.json
/etc/docker/.docker/config.json
/var/lib/docker/.docker/config.json
/var/lib/docker/containers/.docker/config.json

Answer 116

$HOME/.docker/config.json

Question 117

While trying to delete image postgres, you got an error “conflict: unable to remove repository reference “postgres” (must force) – container 1a56b95e073c is using its referenced image adf2b126dda8″. What may be the cause of this error?

A container is using this image
Must use force option to delete an image
Another image is using layers from this image
The image was built locally on this host

Answer 117

A container is using this image

Question 118

Which command is used to remove webapp:v1 image locally?

docker image rm webapp
docker image rm webapp:v1
docker image remove webapp:v1
docker image del webapp:v1

Answer 118

docker image rm webapp:v1

Question 119

Remove all unused images on the Docker host

docker image prune -a
docker image rm -a
docker image delete -a
None of the above

Answer 119

docker image prune -a

Question 120

Display all layers of httpd image along with the size on each layer.

docker image layers httpd
docker image history httpd
docker image inspect httpd
docker images history httpd

Answer 120

docker image history httpd

Question 121

Which command can be used to get the ExposedPorts of a webapp image?

docker container ls
docker image inspect webapp
docker container inspect webapp
docker image ls

Answer 121

docker image inspect webapp

Question 122

How to get the Os field alone of the httpd image?

docker image inspect httpd -f ‘{{.Os}}’
docker image ls | grep Os
docker image history | grep Os
docker image inspect httpd -f ‘{{.OperatingSystem}}’

Answer 122

docker image inspect httpd -f ‘{{.Os}}’

Question 123

Which subcommand will be used to get more info about images?

inspect
load
import
ls

Answer 123

inspect

Question 124

Print the value of ‘Architecture’ and ‘Os’ for a ‘webapp’ image.

docker image inspect webapp -f ‘{{.Os}}’ -f ‘{{.Architecture}}’
docker image inspect webapp -f ‘{{.Os}} {{.Architecture}}’
docker image inspect webapp -f ‘{{.Os}}’, -f ‘{{.Architecture}}’
docker image inspect webapp -f ‘{{.Os .Architecture}}’

Answer 124

docker image inspect webapp -f ‘{{.Os}} {{.Architecture}}’

Question 125

Which command can be used to get a backup of image webapp?

docker image backup webapp -o webapp.tar
docker image save webapp -o webapp.tar
docker container save webapp -o webapp.tar
docker container backup webapp -o webapp.tar

Answer 125

docker image save webapp -o webapp.tar

Question 126

A tarfile – nginx.tar – has been created using the docker image save command. Which command can be used to extract it into your docker host.

docker image import -i nginx.tar
docker image restore -i nginx.tar
docker container restore -i nginx.tar
docker image load -i nginx.tar

Answer 126

docker image load -i nginx.tar

Question 127

A government facility runs a secure data center with no internet connectivity. A new application requires access to docker images hosted on docker hub. What is the best approach to solve this?

Get the Dockerfile of the image and build a local version from within the restricted environment.
Establish a secure link between the host in the restricted environment and docker hub
Pull docker images from a host with access to docker hub, convert to a tarball using docker image save command, and copy to the restricted environment and extract the tarball
Pull docker images from a host with access to docker hub, then push to a registry hosted within the restricted environment.

Answer 127

Pull docker images from a host with access to docker hub, convert to a tarball using docker image save command, and copy to the restricted environment and extract the tarball

Question 128

You have created a nginx container and customized it to create your own webpage. How can you create an image out of it to share with others?

docker image save
docker image export
docker export
You can only create an image using a Dockerfile

Answer 128

docker export

Question 129

How do you restore an image created from the docker export command?

docker container import
docker image import
docker image load
docker image restore

Answer 129

docker image import

Question 130

The “export” command works with Docker images.

True
False

Answer 130

False

Question 131

Export webapp container’s filesystem as a tar archive. Select the right answer

docker export webapp mywebapp.tar
docker image export –output=”mywebapp.tar” webapp
docker image save -i mywebapp.tar
docker container export webapp > mywebapp.tar

Answer 131

docker container export webapp > mywebapp.tar

Question 132

Which of the following commands is used to list the docker images on the Docker Host?

docker images
docker image ls
docker image get
docker ls image

Answer 132

docker image

Question 133

Which of the following commands used to match all images with the com.example.version label?

docker images –label=”com.example.version”
docker images –filter “com.example.version”
docker images –filter “label=com.example.version”
docker images –format “label=com.example.version”

Answer 133

docker images –filter “label=com.example.version”

Question 134

Which of the following is not an instruction supported in the Dockerfile? Select the all right answers.

EXPOSE
ADD
WORKDIR
EXEC

Answer 134

EXEC

Question 135

The … is a text document that contains all the commands a user could call on the command line to assemble an image.

Dockerfile
Docker Compose
.dockerignore
build context

Answer 135

Dockerfile

Question 136

Which method can be used to build an image using existing containers?

docker commit
docker export
docker save
docker load

Answer 136

docker export

Question 137

The container being committed and its processes will be paused while the image is committed.

True
False

Answer 137

True

Question 138

We have a running container named webapp with the nginx image. We added a custom html file to this container. How do we create an image named mynginx from this container?

docker container commit webapp mynginx
docker container commit mynginx webapp
docker container update webapp mynginx
None of the above

Answer 138

docker container commit webapp mynginx

Question 139

The docker container commit is the recommended approach for building a custom image.

True
False

Answer 139

False

Question 140

You are required to create an image from an existing image. What is the recommended approach?

Use docker image export and docker image import command
Use docker container export and docker container import command
Use docker image save and docker image load command
Use docker container commit command

Answer 140

Use docker image save and docker image load command

Question 141

You are required to create an image from an existing container. What is the recommended approach?

Use docker image export and docker image import command
Use docker container export and docker container import command
Use docker container commit command
Use docker container export and docker image import command

Answer 141

Use docker container export and docker image import command

Question 142

FROM python:3.6
RUN pip install flask
COPY . /opt/
EXPOSE 8080
WORKDIR /opt
ENTRYPOINT ["python", "app.py"]

What is the parent image from which this application is created?

ubuntu:latest
python
centos:7
python:3.6

Answer 142

python:3.6

Question 143

FROM python:3.6
RUN pip install flask
COPY . /opt/
EXPOSE 8080
WORKDIR /opt
ENTRYPOINT ["python", "app.py"]

To what location within the container is the application code copied to?

/opt
/app
/root
/var

Answer 143

/opt

Question 144

FROM python:3.6
RUN pip install flask
COPY . /opt/
EXPOSE 8080
WORKDIR /opt
ENTRYPOINT ["python", "app.py"]

When a container is created using the image built with the following Dockerfile, what is the command used to RUN the application inside it.

pip install flask
docker run app.py
app.py
python app.py

Answer 144

python app.py

Question 145

FROM python:3.6
RUN pip install flask
COPY . /opt/
EXPOSE 8080
WORKDIR /opt
ENTRYPOINT ["python", "app.py"]

What is the port of the web application configured for the service to listen within the container?

8080
5000
80
0.0.0.0

Answer 145

What is the port of the web application configured for the service to listen within the container?

8080
5000
80
0.0.0.0

Question 146

Whenever a build is initiated by running the Docker build command, the files under the build context are transferred to the Docker daemon, at a temporary directory under the docker’s filesystem. Which directory are these files stored in?

/var/lib/docker/tmp
/var/lib/docker/image
/var/lib/docker/volumes
/var/lib/docker/plugins

Answer 146

/var/lib/docker/tmp

Question 147

Which of the below commands may be used to build an image with the Dockerfile filename?

docker build .
docker build -f Dockerfile .
docker build -t Dockerfile2 .
docker build -t .

Answer 147

docker build .

docker build -f Dockerfile .

Question 148

While building a docker image from code stored in a remote URL, which command will be used to build from a directory called docker in the branch dev?

docker build https://github.com/kk/dca.git#dev:docker
docker build https://github.com/kk/dca.git#docker:dev
docker build https://github.com/kk/dca.git:dev
docker build https://github.com/kk/dca.gitdev:#docker

Answer 148

docker build https://github.com/kk/dca.git#dev:docker

Question 149

A build’s context is the set of files located in the specified PATH or URL, Which kind of resources can the URL parameter refer to ?

Git repositories
pre-packaged tarball contexts
Path to a local directory

Answer 149

Git repositories

Path to a local directory

Question 150

Choose the correct flag to apply a tag to an image done.

• i
• p
• f
• t

Answer 150

-t

Question 151

If you do not specify a tag name, you can’t build the image.

True
False

Answer 151

False

Question 152

Build an image using a context build under path /tmp/docker and name it webapp.

docker build /tmp/docker
docker build /tmp/docker -t webapp
docker build webapp -t /tmp/docker
docker pull -it /tmp/docker bash

Answer 152

docker build /tmp/docker -t webapp

Question 153

What is the default tag if not specified when building an image with the name webapp?

none
default
latest
v1

Answer 153

latest

Question 154

What is the command to build an image using a Dockerfile.dev file under path /opt/myapp with the name webapp. The current directory you are in is /tmp.

docker build Dockerfile.dev -t webapp /opt/myapp
docker build -f /opt/myapp/Dockerfile.dev /opt/myapp -t webapp
docker build -f Dockerfile.dev /opt/myapp -t webapp
docker build -t Dockerfile.dev -name webapp -f /opt/myapp

Answer 154

docker build -f /opt/myapp/Dockerfile.dev /opt/myapp -t webapp

Question 155

What is the file used to exclude temporary files such as log files or builds from the context during a build?

.git
.gitignore
.dockerignore
None of the above

Answer 155

.dockerignore

Question 156

If the build fails at a particular stage, it repurposes the previous layers from the cache and does not really rebuild them.

True
False

Answer 156

True

Question 157

What is a recommended approach for installing packages and libraries while building an image?

Download packages on the host and use ADD instructions to add them to the image.
Use the ADD instruction to provide a URL to the package on the remote host.
Use the RUN instruction and have the apt-get update and apt-get install commands on the same instruction.
Use the RUN instruction and have the apt-get update and apt-get install commands as separate instructions.

Answer 157

Use the RUN instruction and have the apt-get update and apt-get install commands on the same instruction.

Question 158

Using RUN apt-get update && apt-get install -y ensures your Dockerfile installs the latest package versions with no further coding or manual intervention. This technique is known as …..

Docker-stack
Cache busting
Version pinning
Build-context

Answer 158

Cache busting

Question 159

What is a best practice while installing multiple packages as part of the install instruction?

Add them on the same line
Add them on separate lines separated by a slash in alphanumeric order
Add a separate instruction for each package
Add them on separate lines separated by a slash

Answer 159

Add them on separate lines separated by a slash in alphanumeric order

Question 160

Which among the following scenarios will lead to docker invalidating cache on a given layer?

Change in instruction
Change in a file used with the ADD instruction
Addition of a new instruction at the end of the file
Release of a new version of a package installed with the RUN instruction

Answer 160

Change in instruction

Change in a file used with the ADD instruction

Question 161

…… forces the build to install a particular version of package regardless of what’s in the cache. This technique can also reduce failures due to unanticipated changes in required packages.

Docker-stack
Cache busting
Version pinning
Build-context

Answer 161

version pinning

Question 162

What is a recommended approach to reduce build time while building docker images?

Instructions likely to change more often must be at the top of the Dockerfile
Instructions likely to change more often must be at the bottom of the Dockerfile
Instructions likely to change more often must be in the middle of the Dockerfile
The order of the instructions within the Dockerfile doesn’t matter.

Answer 162

Instructions likely to change more often must be at the bottom of the Dockerfile

Question 163

What is a recommended approach to reduce build time while building docker images?

Instructions likely to change more often must be at the top of the Dockerfile
Instructions likely to change more often must be at the bottom of the Dockerfile
Instructions likely to change more often must be in the middle of the Dockerfile
The order of the instructions within the Dockerfile doesn’t matter.

Answer 163

Instructions likely to change more often must be at the bottom of the Dockerfile

Question 164

A Dockerfile is built from the Ubuntu image as the base image. What would happen to the cache when a new version of the Ubuntu image is made available at Dockerhub?

Cache is invalidated and docker pulls the new image and recreates from scratch.
Cache is not invalidated and docker continues to use existing cache.

Answer 164

The cache is not invalidated and docker continues to use the existing cache.

Question 165

Which option can be used to disable the cache while building a docker image? (Explore the docker documentation for this)

–no-cache=true
–force-rm=true
–cache-from true
None of the above

Answer 165

–no-cache=true

Question 166

COPY instruction only supports the basic copying of local files into the container.

True
False

Answer 166

True

Question 167

What is the right instruction to download a file from “https://file.tar.xz” and copy to “/testdir” in the image?

ADD https://file.tar.xz /testdir
COPY https://file.tar.xz /testdir
RUN https://file.tar.xz /testdir
None of the above

Answer 167

ADD https://file.tar.xz /testdir

Question 168

COPY instruction has some features like local-only tar extraction and remote URL support.

True
False

Answer 168

False

Question 169

Which instruction(s) can be used in the Dockerfile to copy content from the local filesystem into the containers?

ADD
COPY
MOVE
RUN

Answer 169

ADD

COPY

Question 170

Which of the following is the correct format for CMD instruction?

CMD [“executable”,”param1”,”param2”]
CMD [“param1”,”param2”]
CMD command param1 param2
CMD command,param1,param2

Answer 170

CMD [“executable”,”param1”,”param2”]

CMD command param1 param2

Question 171

If CMD is used to provide default arguments for the ENTRYPOINT instruction, both the CMD and ENTRYPOINT instructions should be specified.

True
False

Answer 171

True

Question 172

When a user runs the command docker run my-custom-image sleep 1000

docker overrides the ENTRYPOINT instruction with “sleep 1000”
docker overrides the CMD instruction with “sleep 1000”
docker override ENTRYPOINT instruction with “sleep” and CMD instruction with “1000”

Answer 172

docker overrides the CMD instruction with “sleep 1000”

Question 173

Choose the correct instruction to add the echo “Hello World” command in the Dockerfile.

CMD [echo “Hello World”]
CMD [“echo”, “Hello World”]
CMD [“Hello World”]
None of the above

Answer 173

CMD [“echo”, “Hello World”]

Question 174

What is the output of the following Dockerfile snippet when container runs as docker run -it < image> ?
ENTRYPOINT [“/bin/echo”, “Hello”]
CMD [“world”]

Hello world
Hello
world
world Hello

Answer 174

Hello world

Question 175

What is the output of the following Dockerfile snippet when container runs as docker run -it kk ?
ENTRYPOINT [“/bin/echo”, “Hello”]
CMD [“World”]

Hello kk
Hello
World kk
kk Hello

Answer 175

Hello kk

Question 176

f you list more than one CMD instruction in the Dockerfile then only the last CMD will take effect.

True
False

Answer 176

True

Question 177

A parent image is an image that your image is based on. It refers to the contents of the FROM directive in the Dockerfile.

True
False

Answer 177

True

Question 178

A parent image has FROM scratch in its Dockerfile.

True
False

Answer 178

False

Question 179

While building an image, You have one base image, but there could be multiple parent images.

True
False

Answer 179

True

Question 180

How do you identify if a Docker file is configured to use multi-stage builds?

The Dockerfile has the tag multi-stage at the top
The Dockerfile has multiple FROM instructions
The Dockerfile has multiple RUN instructions
The Dockerfile is built from the scratch image

Answer 180

The Dockerfile has multiple FROM instructions

Question 181

The “–from=0” in the following Dockerfile instruction line refers to:
“COPY –from=0 /go/src/github.com/alexellis/href-counter/app .”

The base image specified in the FROM instruction of the first set of instructions.
The base image specified in the FROM instruction of the second set of instructions.
The image built using the first set of instructions in the Dockerfile.
The image built using the last set of instructions in the Dockerfile

Answer 181

The image built using the first set of instructions in the Dockerfile.

Question 182

By default, the stages are not named, and you refer to them by their integer number, starting with 1 for the first FROM instruction in the multi-stage build.

True
False

Answer 182

False

Question 183

Name the stage which uses nginx as a base image to builder in the Dockerfile.

FROM nginx
FROM nginx AS builder
The last image build
FROM node AS builder

Answer 183

FROM nginx AS builder

Question 184

What is the instruction used to copy a file from an external image named redis not part of any stage in the multi-stage build process. (Refer to the documentation for this one)

–from=redis
–from=0
–copy-from=redis
–copy-from=0

Answer 184

–from=redis

Question 185

You are developing an e-commerce application. The application must store cart details of users temporarily as long as the user’s session is active. What is the recommended approach to storing the cart details with the application deployed as a docker container?

Store the cart details in the /tmp directory of the container
Store the cart details in the memory of the container
Store the cart details in a volume backed by a in-memory cache service like redis

Answer 185

Store the cart details in a volume backed by a in-memory cache service like redis

Question 186

It’s recommended to avoid sending unwanted files to the build context by using .gitignore file to exclude those files.

True
False

Answer 186

False

Question 187

An application you are developing requires an httpd server as frontend, a python application as the backend API server, a MongoDB database and a worker developed in Python. What is the recommended approach in building images for these containers?

Build httpd, python API server, MongoDB database, and Python worker into a single image to allow ease of deployment
Build httpd into an image, MongoDB database to another, and Python API and worker together into a single image
Build separate images for each component of the application

Answer 187

Build separate images for each component of the application

Question 188

Which of the below can help minimize the image size?

Only install necessary packages within the image
Avoid sending unwanted files to the build context using .dockerignore
Combine multiple dependent instructions into a single one and clean up temporary files
Move the instructions that are likely to change most frequently to the bottom of the Dockerfile
Use multi-stage builds

Answer 188

• Only install necessary packages within the image
• Combine multiple dependent instructions into a single one and clean up temporary files
• Use multi-stage builds

Question 189

Which is the recommended approach to install packages following the best practices in Dockerfile?

RUN apt-get update && apt-get install -y git httpd
RUN apt-get update && apt-get install -y \
       git \
       httpd
RUN apt-get update \
RUN apt-get install -y git \
RUN apt-get install -y httpd

Answer 189

RUN apt-get update && apt-get install -y \
       git \
       httpd

Question 190

Which of the below steps can help minimize the build time of images?

Only install necessary packages within the image
Avoid sending unwanted files to the build context using .dockerignore
Combine multiple dependent instructions into a single one and clean up temporary files
Move the instructions that are likely to change most frequently to the bottom of the Dockerfile
Use multi-stage builds

Answer 190

• Avoid sending unwanted files to the build context using .dockerignore
• Move the instructions that are likely to change most frequently to the bottom of the Dockerfile

Question 191

Which of the following tag image will get when creating a redis container with image redis?
docker run -itd –name redis redis

none
default
v1
latest

Answer 191

latest

Question 192

Which of the below statements are true:

By default a container runs with 1 vCPU and 500 MB of memory
By default a container runs with unlimited CPU and Memory resources
By default a container runs with 0.5 vCPU and 500 MB of memory
By default a container runs with unlimited vCPU and 500 MB of memory

Answer 192

By default a container runs with unlimited CPU and Memory resources

Question 193

What will happen if the –memory-swap is set to -1?

the container does not have access to swap.
the setting is ignored, and the value is treated as unset.
the container is allowed to use unlimited swap.
None of the above

Answer 193

the container is allowed to use unlimited swap.

Question 194

Each container gets a CPU share of …. assigned by default.

256
512
1024
2048

Answer 194

1024

Question 195

What is a linux feature that prevents a process within the container to access raw sockets?

Control Groups (CGroups)
Namespaces
Kernel Capabilities
Network Namespaces

Answer 195

Kernel Capabilities

Question 196

By default, all containers get the same share of CPU cycles. How to modify the shares?

docker container run –cpu-shares=512 nginx
docker container run –cpuset-cups=512 nginx
docker container run –cpu-quota=512 nginx
docker container run –cpus=512 nginx

Answer 196

docker container run –cpu-shares=512 nginx

Question 197

Which command is used to list the default available networks? 
 docker network --filter
 docker network get
 docker network ls
 None of the above

Answer 197

docker network ls

Question 198

Which command is used to see the network settings and IP address assigned to a container with id c164825bb3d3 that uses the myapp image?

docker inspect myapp
docker container ls myapp
docker container ls c164825bb3d3
docker inspect c164825bb3d3

Answer 198

docker inspect c164825bb3d3

Question 199

What is the default network driver used on a container if you haven’t specified one?

host
bridge
overlay
Macvlan

Answer 199

bridge

Question 200

Overlay networks connect multiple Docker daemons together and enable swarm services to communicate with each other.

True
False

Answer 200

True

Question 201

If you use the …… network mode for a container, that container’s network stack is not isolated from the Docker host (the container shares the host’s networking namespace), and the container does not get its own IP-address allocated.

host
bridge
overlay
Macvlan

Answer 201

host

Question 202

How to get the subnet, gateway of the network c0a0b59a3807?

docker info c0a0b59a3807
docker container inspect c0a0b59a3807
docker network inspect c0a0b59a3807
docker inspect c0a0b59a3807

Answer 202

docker network inspect c0a0b59a3807

Question 203

Which of the following commands would create a user-defined bridge network called my-net?

docker network create my-net
docker create network my-net
docker network create -d bridge my-net
docker network create –type bridge my-net
docker network create –driver bridge my-net

Answer 203

docker network create my-net

docker network create –driver bridge my-net

Question 204

What is the command to connect a running container with name myapp to the existing bridge network my-net?

docker container connect myapp my-net
docker container attach myapp my-net
docker network connect my-net myapp
docker network connect myapp my-net

Answer 204

docker network connect my-net myapp

Question 205

What is the command to remove all unused networks?

docker network create my-net
docker network rm my-net
docker network prune
docker network rm –all

Answer 205

docker network prune

Question 206

What is the command to remove the my-net network?

docker network create my-net
docker network rm my-net
docker network connect my-net
None of the above

Answer 206

docker network rm my-net

Question 207

Which of the following commands would create a user-defined bridge network called dev-net?

docker network create dev-net
docker create network dev-net
docker network create -d bridge dev-net
docker network create –type bridge dev-net
docker network create –driver bridge dev-net

Answer 207

docker network create dev-net
docker network create -d bridge dev-net
docker network create –driver bridge dev-net

Question 208

What is the command to connect a running container with name myapp to the existing bridge network dev-net?

docker container connect myapp dev-net
docker container attach myapp dev-net
docker network connect dev-net myapp
docker network connect myapp dev-net

Answer 208

docker network connect dev-net myapp

Question 209

What is the command to remove all unused networks from the Docker host?

docker network create cisco-net
docker network rm web-net
docker network prune
docker network rm –all

Answer 209

docker network prune

Question 210

What is the command to delete the network named connector?

docker network prune connector
docker network rm connector
docker network delete connector
None of the above

Answer 210

docker network rm connector

Question 211

What is the command to list all available networks?

docker network ls
docker network show
docker network display
docker get network

Answer 211

docker network ls

Question 212

Which command is used to see the IP address and other network settings assigned to a container with id 33373b1ccc3f that uses the wordpress image?

docker inspect wordpress
docker container ls wordpress
docker container ls 33373b1ccc3f
docker inspect 33373b1ccc3f

Answer 212

docker inspect 33373b1ccc3f

Question 213

What is the default network driver used on a container if you haven’t specified one?

host
bridge
overlay
All of the above

Answer 213

What is the default network driver used on a container if you haven’t specified one?

host
bridge
overlay
All of the above

Question 214

If you use the … network mode for a container, that container’s network stack is not isolated from the Docker host (the container shares the host’s networking namespace), and the container does not get its own IP-address allocated.

bridge
overlay
host
none

Answer 214

host

Question 215

Which command is used to disconnect the my-net network from the redis container?

docker network rm redis my-net
docker network disconnect redis my-net
docker network disconnect my-net redis
docker network disconnect redis

Answer 215

docker network disconnect my-net redis

Question 216

Which command is used to see the details of the subnet and gateway of network id ce982a9edf65?

docker info ce982a9edf65
docker container inspect ce982a9edf65
docker show ce982a9edf65
docker network inspect ce982a9edf65

Answer 216

docker network inspect ce982a9edf65

Question 217

By default, all files created inside a container are stored on a writable container layer.

True
False

Answer 217

True

Question 218

Volumes are the preferred mechanism for persisting data generated by and used by Docker containers.

True
False

Answer 218

True

Question 219

What is the command to remove unused volumes?

docker container rm my-vol
docker volume rm my-vol
docker volume prune
docker volume rm –all

Answer 219

docker volume prune

Question 220

What is the command to create a volume with the name my-vol?

docker volume create my-vol
docker create volume my-vol
docker volume prune
docker volume rm all

Answer 220

docker volume create my-vol

Question 221

What is the command to list volumes?

docker volume ls
docker volume prune
docker volume get
None of the above

Answer 221

docker volume ls

Question 222

What is the command to get details of the volume my-vol such as the driver, mountpoint, volumename, ..etc?

docker volume inspect my-vol
docker volume fetch my-vol
docker volume get my-vol
docker volume ls my-vol

Answer 222

docker volume inspect my-vol

Question 223

Which command is used to remove the my-vol volume?

docker volume del my-vol
docker volume remove my-vol
docker volume prune my-vol
docker volume rm my-vol

Answer 223

docker volume remove my-vol

docker volume rm my-vol

Question 224

The volumes are mounted as “readonly” by default inside the container if no options are specified.

True
False

Answer 224

False

Question 225

You can remove a vol1 which is in use by a container using the command docker volume rm –force vol1.

True
False

Answer 225

False

Question 226

Which option is used to mount a volume?

-v
– -volume
– -mount
–volume-mount

Answer 226

• v
• -mount
• -volume

Question 227

Which among the below is a correct command to start a webapp container with the volume vol2, mounted to the destination directory /app?

docker run -d –name webapp –mount source=vol2,target=/app httpd
docker run -d –name webapp -v vol2:/app httpd
docker run -d –name webapp –volume vol2:/app httpd

Answer 227

docker run -d –name webapp –mount source=vol2,target=/app httpd

docker run -d –name webapp -v vol2:/app httpd

docker run -d –name webapp –volume vol2:/app httpd

Question 228

Which among the below is a correct command to start a webapp container with the volume vol3, mounted to the destination directory /opt in readonly mode?

docker run -d –name webapp –mount source=vol3,target=/opt,readonly httpd
docker run -d –name webapp -v vol3:/opt:ro httpd
docker run -d –name webapp -v vol3:/opt:readonly httpd
docker run -d –name webapp –volume vol3:/opt:ro httpd
docker run -d –name webapp –mount source=vol3,target=/opt,ro httpd

Answer 228

docker run -d –name webapp –mount source=vol3,target=/opt,readonly httpd

docker run -d –name webapp -v vol3:/opt:ro httpd

docker run -d –name webapp –volume vol3:/opt:ro httpd

Question 229

By default, all files inside an image are in a writable layer.

True
False

Answer 229

False

Question 230

Using …… we can configure containers and communication between them in a declarative way.

Docker Compose
Dockerfile
Device Mapper
Build-context

Answer 230

Docker Compose

Question 231

…….. is a YAML file that contains details about the services, networks, and volumes for setting up a Docker application.

Dockerfile
Docker Compose
.dockerignore
.env

Answer 231

Docker Compose

Question 232

Which command can be used to create and start containers in foreground using the existing docker-compose.yml?

docker-compose up
docker-compose ps
docker-compose logs
docker-compose stop

Answer 232

docker-compose up

Question 233

Which command can be used to create and start containers in the background or detached mode in composing the existing docker-compose.yml?

docker-compose up
docker-compose up –background
docker-compose up –detach
docker-compose up -d

Answer 233

docker-compose up –detach

docker-compose up -d

Question 234

…… is the command to list the containers created by compose file.

docker-compose ls
docker-compose ps
docker-compose list

Answer 234

docker-compose ps

Question 235

…… is the command to check the logs for the whole stack defined inside compose file.

docker-compose up
docker-compose ps
docker-compose logs
docker-compose up -d

Answer 235

docker-compose logs

Question 236

Which command can be used to stop (only and not delete) the whole stack of containers created by compose file?

docker-compose down
docker-compose stop
docker-compose destroy
docker-compose halt

Answer 236

docker-compose stop

Question 237

docker-compose stop command stops and removes the whole stack of containers created by compose file.

True
False

Answer 237

False

Question 238

Select the right answer. Which command can be used to delete the application stack created using compose file?

docker-compose rm
docker-compose stop
docker-compose down
docker-compose destroy

Answer 238

docker-compose down

Question 239

Compose files that doesn’t declare a version are considered “version 0”.

True
False

Answer 239

False

Question 240

Compose files using the version 2 and version 3 syntax must indicate the version number at the root of the document.

True
False

Answer 240

True

Question 241

With the docker-compose up command, we can run containers on multiple docker hosts.

True
False

Answer 241

False

Question 242

version: "3.8"
services:
  web:
    build: .
    depends_on:
      - db
      - redis
    volumes:
      - .:/code
      - logvolume01:/var/log
    ports:
      - "8080:80"
  redis:
    image: redis
  db:
    image: postgres
volumes:
  logvolume01: {}

What is the host port on which the web application will be exposed on?

80
8080
Version 1
foobar.com

Answer 242

8080

Question 243

version: "3.8"
services:
  web:
    build: .
    depends_on:
      - db
      - redis
    volumes:
      - .:/code
      - logvolume01:/var/log
    ports:
      - "8080:80"
  redis:
    image: redis
  db:
    image: postgres
volumes:
  logvolume01: {}

Which of the following statements are true?

All of the web, redis and db images will be built before deploying containers.
The redis image will be built and the web image will be pulled from Dockerhub if it doesn’t already exist on the host.
The web image will be built and the redis image will be pulled from Dockerhub if it doesn’t already exist on the host.
All images will be pulled from Dockerhub.

Answer 243

The web image will be built and the redis image will be pulled from Dockerhub if it doesn’t already exist on the host.

Question 244

version: "3.8"
services:
  web:
    build: .
    depends_on:
      - db
      - redis
    volumes:
      - .:/code
      - logvolume01:/var/log
    ports:
      - "8080:80"
  redis:
    image: redis
  db:
    image: postgres
volumes:
  logvolume01: {}

How can the web application address redis?

Using the container ID generated by redis
Using the name redis
Using the internal IP address of the redis container
By exposing port 6379 of redis container on the host and then using hosts IP

Answer 244

using the name redis

Question 245

version: "3.8"
services:
  web:
    build: .
    depends_on:
      - db
      - redis
    volumes:
      - .:/code
      - logvolume01:/var/log
    ports:
      - "8080:80"
  redis:
    image: redis
  db:
    image: postgres
volumes:
  logvolume01: {}

What kind of volume mount is configured on the web application for the /code directory inside the container?

Volume Mount
Bind Mount

Answer 245

Bind Mount

Question 246

version: "3.8"
services:
  web:
    build: .
    depends_on:
      - db
      - redis
    volumes:
      - .:/code
      - logvolume01:/var/log
    ports:
      - "8080:80"
  redis:
    image: redis
  db:
    image: postgres
volumes:
  logvolume01: {}

What kind of volume mount is configured on the web application for the /var/log directory inside the container?

Volume mount
Bind mount

Answer 246

Volume mount

Question 247

version: "3.8"
services:
  web:
    build: .
    depends_on:
      - db
      - redis
    volumes:
      - .:/code
      - logvolume01:/var/log
    ports:
      - "8080:80"
  redis:
    image: redis
  db:
    image: postgres
volumes:
  logvolume01: {}

Which is the correct statement referring to the following Compose file?

The depends_on configuration is not supported in Compose version 3
db and redis services will be started before web service
web service will be started before db and redis services
None of the above

Answer 247

db and redis services will be started before web service

Question 248

What is the command to see the running process inside of containers created by compose file?

docker-compose top
docker-compose stats
docker top
docker stats

Answer 248

docker-compose top

Question 249

What technologies can be used to group multiple machines together into a single cluster to run applications in the form of containers?

Swarm
Kubernetes
Mesos
Openshift

Answer 249

Swarm
Kubernetes
Mesos
Openshift

Question 250

What are the advantages of container orchestration?

High availability
Auto Scaling
Self-healing
Declarative

Answer 250

High availability
Auto Scaling
Self-healing
Declarative

Question 251

Swarm nodes can be physical or virtual, on the cloud or on-prem that have Docker engine installed on it.

True
False

Answer 251

True

Question 252

A swarm cluster consists of at least one manager node and one or more worker nodes.

True
False

Answer 252

True

Question 253

The manager in the swarm cluster receives instructions or tasks from the worker node and runs containers.

True
False

Answer 253

False

Question 254

Manager nodes are dedicated to management tasks only and cannot run workloads.

True
False

Answer 254

False

Question 255

Who is responsible for maintaining the desired state of the swarm cluster and taking necessary actions if a node was to fail or a new node was added to the cluster?

manager node
worker node
slave node
worker, slave nodes

Answer 255

manager node

Question 256

You can promote a worker node to a manager node.

True
False

Answer 256

True

Question 257

What feature of swarm closely relates to this use case – “If an instance of an application crashes, it is immediately replaced by a new one”?

Rolling updates
Self-healing
Scaling
Load Balancing

Answer 257

Self-healing

Question 258

The communication between the nodes in the swarm cluster is not secured by default.

True
False

Answer 258

False

Question 259

Is it possible to promote a worker node to manager in swarm?

Yes
No

Answer 259

Yes

Question 260

The command docker node promote can be executed on any node “manager or worker”.

True
False

Answer 260

False

Question 261

Promote worker1 to a manager node. Select the right answer.

docker promote node worker1
docker node promote worker1
docker swarm node promote worker1
docker swarm promote node worker1

Answer 261

docker node promote worker1

Question 262

Change manager1 to a worker node. Select the right answer.

docker swarm node demote manager1
docker demote node manager1
docker node demote manager1
docker node demote manager1 worker

Answer 262

docker node demote manager1

Question 263

If you have one manager in your swarm cluster, is it possible to demote it to a worker node?

True
False

Answer 263

False

Question 264

What does the Reachable status of a node indicate in docker swarm?

The node is a worker node and is reachable
The node is a manager node and is reachable
The node is a manager node and is reachable and is not the leader
The node is a manager node and is the leader

Answer 264

The node is a manager node and is reachable and is not the leader

Question 265

Which command is used to check the status of manager/worker nodes?

docker swarm ls
docker node ps
docker node ls
docker swarm show nodes

Answer 265

docker node ls

Question 266

We want to perform maintenance tasks on node – worker1 – for performing patching and updates. Select the best way to achieve this.

docker node update –availability drain worker1
docker node update –availability active worker1
docker node rm worker1
None of the above

Answer 266

docker node update –availability drain worker1

Question 267

When a worker node becomes active again after draining, the old containers will go back to this node.

True
False

Answer 267

False

Question 268

We have a single manager 2 worker node swarm cluster. All three nodes are hosting workload. What is the sequence of activities to remove the manager node from the swarm cluster?

Drain the node, and run docker swarm leave.
Demote to a worker node, drain the node and run docker swarm leave.
Promote a worker node to master, demote manager to worker, drain the node and run docker swarm leave.
Add a new worker node, drain the manager node, and run docker swarm leave.

Answer 268

Promote a worker node to master, demote manager to worker, drain the node and run docker swarm leave.

Question 269

It is recommended to have one manager in your cluster?

True
False

Answer 269

False

Question 270

The manager node is responsible for maintaining the cluster state, distributing and ensuring the state of containers and services across all workers.

True
False

Answer 270

True

Question 271

Which of the below statements are true when you have more than 1 manager nodes?

All decisions are made by all the managers at once.
All decisions are made by each manager turn by turn in a round-robin fashion.
All decisions are made by 1 manager who is the leader.

Answer 271

All decisions are made by 1 manager who is the leader.

Question 272

…. is responsible for making sure that all the manager nodes that are in charge of managing and scheduling tasks in the cluster, are storing the same consistent state.

CFS
Scheduler
Raft consensus
Leader

Answer 272

Raft consensus

Question 273

Out of a total of 3 masters if one node was to fail or was not responding at that moment and only two nodes were available,the decision to add the new worker can still be made with an agreement between the two available nodes.

True
False

Answer 273

True

Question 274

…. is defined as the minimum number of managers required to be present for carrying out cluster management tasks.

Majority
Fault tolerance
Quorum
Single failure

Answer 274

Quorum

Question 275

What is the maximum number of managers possible in a swarm cluster?

3
5
7
No limit

Answer 275

No Limit

Docker recommends 7

Question 276

What is the maximum number of managers recommended by Docker in a swarm cluster?

3
5
7
No limit

Answer 276

7

Question 277

Which formula can be used to calculate the Quorum of N nodes?

N + 1
N+1 / 2
N-1/2
N /2 -1

Answer 277

N-1/2

Question 278

Which formula can be used to calculate the fault tolerance of N nodes?

N + 1
N+1 / 2
N / 2 +1
(N-1)/2

Answer 278

(N-1)/2

Question 279

It is recommended to have an even number of master nodes.

True
False

Answer 279

False

Question 280

Assume that you have 3 managers in your cluster, what will happen if 2 managers fail at the same time? Select the all-right answers.

The services hosted on the available worker nodes will continue to run.
The services hosted on the available worker nodes will stop running.
New services/workers can be created or added.
New services/workers can’t be created or added.

Answer 280

The services hosted on the available worker nodes will continue to run.

New services/workers can’t be created or added.

Question 281

How many manager nodes must be online in a cluster with 13 manager nodes for the swarm cluster to continue to operate?

3
1
6
7

Answer 281

7

Question 282

How many manager nodes must be online in a cluster with 7 manager nodes for the swarm cluster to continue to operate?

3
1
4
5

Answer 282

4

Question 283

Among the below what is the recommended number of manager nodes as per best practices?

9
7
1
4

Answer 283

7

Question 284

You have 3 data centers and 9 managers. How best should you distribute the managers between them to withstand site-wide disruptions?

3-3-3
9-0-0
4-4-1
4-3-2

Answer 284

3-3-3

Question 285

You have 3 data centers and 11 managers. How best should you distribute the managers between them to withstand site-wide disruptions?

4-3-3
4-4-3
4-5-2
9-0-2

Answer 285

4-4-3

Question 286

You have 3 data centers and 13 managers. How best should you distribute the managers between them to withstand site-wide disruptions?

5-5-3
6-6-1
7-5-1
7-3-3

Answer 286

5-5-3

Question 287

You have 3 data centers and 7 managers. How best should you distribute the managers between them to withstand site-wide disruptions?

4-2-1
3-2-3
3-2-2
3-1-3

Answer 287

3-2-2

Question 288

Which of the below statements are true?

By default, manager nodes host workloads. You must explicitly configure it not to.
By default, manager nodes do not host workloads. You must explicitly configure it to host workloads.

Answer 288

By default, manager nodes host workloads. You must explicitly configure it not to.

Question 289

The RAFT logs are stored in memory on the manager nodes.

True
False

Answer 289

False

Question 290

The RAFT logs are stored on disk and not protected.

True
False

Answer 290

False

Question 291

The default behavior requires you to unlock the swarm when a new node joins the swarm cluster.

True
False

Answer 291

False

Question 292

After restarting the docker service and trying to run docker service ls, you get an error “Error response from daemon: Swarm is encrypted and needs to be unlocked before it can be used. How can you solve this error?

docker swarm leave
docker swarm update
docker swarm lock
docker swarm unlock

Answer 292

docker swarm unlock

Question 293

Which command can be used to return the current key which is used inside the cluster?

docker swarm lock-key
docker swarm lock –autolock=true
docker swarm unlock –autolock=true
docker swarm unlock-key

Answer 293

docker swarm unlock-key

Question 294

Which command can be used to enable auto lock on an existing swarm?

docker swarm update –autolock=true
docker swarm lock –autolock=true
docker swarm set –autolock=true
docker swarm unlock-key

Answer 294

docker swarm update –autolock=true

Question 295

…. are one or more instances of a single application that runs across the Swarm Cluster.

docker stack
services
pods
None of the above

Answer 295

services

Question 296

Which command can be used to run an instance on swarm?

docker container run -d webapp
docker container create webapp
docker service create webapp
docker swarm service create webapp

Answer 296

docker service create webapp

Question 297

What is the command to run 3 instances of httpd on a swarm cluster?

docker swarm service create –instances=3 httpd
docker swarm service create –replicas=3 httpd
docker service create –instances=3 httpd
docker service create –replicas=3 httpd

Answer 297

docker service create –replicas=3 httpd

Question 298

What component is responsible for creating tasks in a swarm?

scheduler
dispatcher
orchestrator
allocator

Answer 298

orchestrator

Question 299

What component is responsible for instructing a worker to run a task?

scheduler
dispatcher
orchestrator
allocater

Answer 299

scheduler

Question 300

The …. assigns tasks to nodes in swarm.

scheduler
dispatcher
orchestrator
allocator

Answer 300

dispatcher

Question 301

The …. is used to allocate IP addresses to tasks in swarm.

scheduler
dispatcher
orchestrator
allocator

Answer 301

allocator

Question 302

Create a swarm service webapp with image httpd and expose port 8080 on host to port 80 in container.

docker container run –name=webapp -p 8080:80 httpd
docker service create –name=webapp -p 8080:80 httpd
docker service create –name=webapp -p 8800:80 –instances=3 httpd
docker service create –replicas=3 httpd

Answer 302

docker service create –name=webapp -p 8080:80 httpd

Question 303

Which command can be used to list the running service inside the swarm?

docker service ps
docker service ls
docker container ps
docker container ls

Answer 303

docker service ls

Question 304

Which command can be used to list the tasks that are running as part of a specified service?

docker service ps SERVICE-NAME
docker service ls
<code>docker container ps SERVICE-NAME</code>
<code>docker container ls</code>

Answer 304

docker service ps SERVICE-NAME

Question 305

List more details about each service in a human-readable format.

docker service ps SERVICE-NAME –pretty
docker container ps SERVICE-NAME –pretty
docker service inspect SERVICE-NAME –pretty
None of the above

Answer 305

docker service inspect SERVICE-NAME –pretty

Question 306

Which command can be used to get the logs of a swarm service?

docker container logs SERVICE-NAME
docker service logs SERVICE-NAME
docker swarm log SERVICE-NAME
docker swarm logs SERVICE-NAME

Answer 306

docker service logs SERVICE-NAME

Question 307

Delete a webapp service from your cluster.

docker swarm leave webapp
docker service rm webapp
docker service rollback webapp
docker service del webapp

Answer 307

docker service rm webapp

Question 308

How many replicas does a service created with the command – ‘docker service create webapp’ have?

0
1
2
3

Answer 308

1

Question 309

Which command can be used to increase the number of replicas from 2 to 4 of webapp? Select the all right answer.

docker service update –replicas=4 webapp
docker service update –replicas=2 webapp
docker service scale webapp=2
docker service scale webapp=4

Answer 309

docker service update –replicas=4 webapp

Question 310

The webapp:v1 had some bugs and we fixed them in webapp:v2. We want to apply webapp:v2 to webapp service. Select the right answer.

docker service update –image=webapp:v1 webapp
docker service update –image=webapp:v2 webapp
docker service update webapp webapp:v1
docker service update webapp webapp:v2

Answer 310

docker service update –image=webapp:v2 webapp

Question 311

An image update operation in a swarm service happens all at once by default.

True
False

Answer 311

False

Question 312

Which option of the docker service command can be used to update 4 replicas of mywebapp service at a time?

• -update-delay 4
• -update-parallelism 4
• -placement-pref-add 4
• -replicas 4

Answer 312

–update-parallelism 4

Question 313

If at any time during an update a task returns FAILED, the default behaviour of the scheduler is to rollback the changes unless specified otherwise.

True
False

Answer 313

False

It is to pause

Question 314

What option may be used to change the default behavior of a failed task during an update in a swarm?

• -update-failure-action
• -update-parallelism
• -update-delay
• -placement-pref-add

Answer 314

–update-failure-action

Question 315

What are the actions which can be used with <code>–update-failure-action</code> ?

 pause
 continue
 stop
 rollback
 rolling-update

Answer 315

pause
continue
rollback

Question 316

After an update, we realized that something is wrong with the new version and we want to revert back to the old version. How can we achieve that?

docker service update rollback webapp
docker service rollback webapp
docker service rm webapp
docker service leave webapp

Answer 316

docker service rollback webapp

Question 317

The default type of a service in docker swarm is global.

True
False

Answer 317

False

Question 318

With a global service, you can specify a minimum number of replicas for the service.

True
False

Answer 318

False

Question 319

A global service will always deploy exactly one instance of the application on all the nodes in the cluster.

True
False

Answer 319

True

Question 320

With a global service if a node is removed from the cluster, then that instance is removed as well and is rescheduled on another available node.

True
False

Answer 320

False

Question 321

Create a replicated service webapp with 2 replicas. Select the all-right answer.

docker service create –replicas=2 webapp
docker service create –mode=replicated –replicas=2 webapp
docker service create –mode=global –replicas=2 webapp
docker service create –replicas=2 web

Answer 321

docker service create –replicas=2 webapp

docker service create –mode=replicated –replicas=2 webapp

Question 322

Deploy exactly one instance of the application on all the nodes in the cluster.

docker service create –replicas=1 webapp
docker service create –mode=replicated –replicas=1 webapp
docker service create –mode=global –replicas=1 webapp
docker service create –mode=global webapp

Answer 322

docker service create –mode=global webapp

Question 323

How to get the service type of webapp service? Select the all-right answer.

docker container inspect webapp
docker service inspect webapp
docker container ls
docker service ls

Answer 323

docker service inspect webapp

docker service ls

Question 324

You are required to deploy an agent of Splunk on all nodes in the swarm cluster to monitor the health of the nodes and gather logs. What is the best approach to achieve this?

Deploy the agent as a docker container on each node in the cluster. Use a cron job to set this up.
Deploy the agent as a global service in the swarm cluster.
Deploy the agent as a replicated service with the replica count equal to the number of worker nodes in the swarm cluster.

Answer 324

Deploy the agent as a global service in the swarm cluster.

Question 325

By default, when we create a service, the tasks may be assigned to any of these nodes without any additional considerations as long as they have sufficient hardware resources.

True
False

Answer 325

True

Question 326

If you specify multiple placement constraints, the service only deploys onto nodes where they are all met.

True
False

Answer 326

True

Question 327

Which option can be used to control the workload placements with the help of labels and constraints?

replicated services
global services
placement constraints
resource restrictions

Answer 327

placement constraints

Question 328

What is the command to deploy a service named webapp on a node which has a ‘type=cpu-optimized’ label.

docker service create –constraint=node.labels.type==cpu-optimized webapp
docker service create –labels type==cpu-optimized webapp
docker service create –container-label type==cpu-optimized webapp
None of the above

Answer 328

docker service create –constraint=node.labels.type==cpu-optimized webapp

Question 329

What is the command to apply <code>’disk=ssd'</code> label to <code>worker1</code> in a swarm cluster.

docker node update –label-add disk=ssd worker1
docker node update –label-rm disk=ssd worker1
docker service update –labels disk=ssd worker1
docker service update –container-label disk=ssd worker1

Answer 329

docker node update –label-add disk=ssd worker1

Question 330

Bridge is the default network a container gets attached to

True
False

Answer 330

True

Question 331

If you use the host network mode for a container, that container’s network stack is not isolated from the Docker host as the container shares the host’s networking namespace.

True
False

Answer 331

True

Question 332

The …. network disables all networking. Usually used in conjunction with a custom network driver.

host
bridge
overlay
none

Answer 332

none

Question 333

The …. network connects multiple Docker daemons together and enables swarm services to communicate with each other.

host
overlay
bridge
none

Answer 333

overlay

Question 334

When you initialize a Docker Swarm cluster it creates a new network of type overlay which is an internal private network that spans across all the nodes participating in the swarm cluster.

True
False

Answer 334

True

Question 335

When you create a swarm service and do not connect it to a user-defined overlay network, it connects to the …. network by default.

host
bridge
macvlan
ingress

Answer 335

ingress

Question 336

Which network will be created when you initialize a swarm or join a Docker host to an existing swarm?

host
bridge
macvlan
ingress

Answer 336

bridge

ingress

Question 337

What is the command to create an overlay network driver called my-overlay?

docker network create my-overlay
docker create network my-overlay
docker network create -d overlay my-overlay
docker network create overlay my-overlay

Answer 337

docker network create -d overlay my-overlay

Question 338

docker network inspect ingress
docker network -d rm ingress
docker network rm ingress
docker network create ingress

Answer 338

docker network rm ingress

Question 339

Which command is used to list available networks in the swarm cluster?

docker network –filter
docker network get
docker network ls
None of the above

Answer 339

docker network ls

Question 340

Create an overlay network driver called my-overlay with subnet 10.15.0.0/16 using a docker command.

docker network create my-overlay
docker network create –driver overlay –subnet 10.15.0.0/16 my-overlay
docker network create -d overlay -subnet 10.15.0.0/16
docker network create overlay my-overlay

Answer 340

docker network create –driver overlay –subnet 10.15.0.0/16 my-overlay

Question 341

When you create an overlay network, only containers created as part of a swarm service can attach to it by default.

True
False

Answer 341

True

Question 342

Create an overlay network that can also be connected by standalone containers that were not created as part of a swarm service.

docker network create –driver overlay –attachable my-overlay-network
docker network create –driver overlay –subnet 10.15.0.0/16 my-overlay-network
docker network create –driver overlay –opt encrypted my-overlay-network
docker network create –driver overlay my-overlay-network

Answer 342

docker network create –driver overlay –attachable my-overlay-network

Question 343

By default, all swarm service management traffic is encrypted using …. algorithm.

TKIP
DES
AES
RSA

Answer 343

AES

Question 344

Encrypt the application data and enable IPSEC encryption while creating the overlay network called my-overlay-network using a docker command.

docker network create –driver overlay –opt encrypted my-overlay-network
docker network create –driver overlay -o encrypted=true my-overlay-network
docker network create -d overlay –encrypted my-overlay

Answer 344

docker network create –driver overlay –opt encrypted my-overlay-network
docker network create –driver overlay -o encrypted=true my-overlay-network

Question 345

Delete an overlay network driver called my-overlay using a docker command.

docker network rm my-overlay
docker create network -d my-overlay
docker rm network my-overlay
docker network rm -d my-overlay

Answer 345

docker network rm my-overlay

Question 346

Remove all of the unused networks using a docker command.

docker network rm my-overlay-network
docker network prune
docker rm network my-overlay-network
docker network rm -all

Answer 346

docker network prune

Question 347

Which port should be opened to allow the overlay and ingress network traffic?

2377
7946
4789
4946

Answer 347

4789

Question 348

The …. port should be opened to allow communication among nodes/Container Network Discovery.

2377
7946
4789
4946

Answer 348

7946

Question 349

Map UDP port 80 in the container to port 5000 on the overlay network using the my-web-server image.

docker service create -p 80:5000/udp my-web-server
docker service create –publish published=80,target=5000,protocol=udp my-web-server
docker service create -p 5000:80/udp my-web-server
docker service create –publish published=5000,target=80,protocol=udp my-web-server

Answer 349

docker service create -p 5000:80/udp my-web-server

docker service create –publish published=5000,target=80,protocol=udp my-web-server

Question 350

You have a legacy application that monitors network traffic and expects to be directly connected to the physical network. What network driver would you recommend?

host
bridge
macvlan
ingress

Answer 350

macvlan

Question 351

Which among the below networks are used to establish connectivity between containers on different hosts?

 Bridge
 MACVlan
 None
 Overlay
 Host
 IPVlan

Answer 351

MACVlan
Overlay
IPVlan

Question 352

Macvlan network driver assigns a MAC address to each container’s virtual network interface, making it appear to be a physical network interface directly connected to the physical network.

True
False

Answer 352

True

Question 353

The routing mesh enables each node in the swarm to accept connections on published ports for any service running in the swarm, even if there’s no task running on the node.

True
False

Answer 353

True

Question 354

Docker requires an external DNS server to be configured during installation to help the containers resolve each other using the container name.

True
False

Answer 354

False

Question 355

The built-in DNS server in Docker always runs at IP address ….

127. 0.0.11
128. 0.0.1
129. 17.0.3
130. 17.0.1

Answer 355

127.0.0.11

Question 356

Attach the application my-web-server to a service so that we can access it using its name with the existing overlay network driver my-overlay.

docker service create –name=my-service my-web-server
docker service create –name=my-web-server my-web-server
docker service create –name=my-web-server –network=my-overlay my-web-server
docker service create –publish published=5000,target=80,protocol=udp my-web-server

Answer 356

docker service create –name=my-web-server –network=my-overlay my-web-server

Question 357

The services only under the same network will get resolved with their names so all of the micro-service components should be under the same network so that they can resolve each other.

True
False

Answer 357

True

Question 358

Attach the application my-web-server to a service so that we can access it using its name with the existing overlay network driver my-overlay and the custom DNS 8.8.8.8

docker service create –name=my-service –dns=8.8.8.8 my-web-server
docker service create –name=my-web-server –dns=8.8.8.8 my-web-server
docker service create –name=my-web-server –dns=8.8.8.8 –network=my-overlay my-web-server
docker service create –name=my-web-server –network=my-overlay my-web-server

Answer 358

docker service create –name=my-web-server –dns=8.8.8.8 –network=my-overlay my-web-server

Question 359

Service Discovery allows containers and services to locate and communicate with each other with their names.

True
False

Answer 359

True

Question 360

The ….. is a packaged form of an application that has its own dependencies and runs in its own isolated environment.

stack
service
docker image
container

Answer 360

container

Question 361

The ….. is one or multiple instances of the same type of container that runs on a single node or across multiple nodes in a swarm cluster.

stack
service
docker image
container

Answer 361

service

Question 362

The ….. is a group of interrelated services that together form an entire application.

stack
service
docker image
container

Answer 362

stack

Question 363

We must use version “2” and above of docker-compose file for stack configurations as Version “3” comes with support for a new property called deploy which is used by docker swarm for stack-related configurations.

True
False

Answer 363

False

Question 364

To list stacks, run …

docker stack deploy
docker stack ls
docker stack services
docker stack ps

Answer 364

docker stack ls

Question 365

To list the services created by a stack, run …

docker stack deploy
docker stack ls
docker stack services
docker stack ps

Answer 365

docker stack services

Question 366

Which command can be used to list the tasks in a stack named <code>webapp</code>?

docker stack deploy webapp
docker stack ls webapp
docker stack services webapp
docker stack ps webapp

Answer 366

docker stack ps webapp

Question 367

Which command can be used to remove a webapp stack?

docker stack deploy webapp
docker stack ls webapp
docker stack services webapp
docker stack rm webapp

Answer 367

docker stack rm webapp

Question 368

You could restrict the resources assigned to a service using the …. property in the docker stack.

resources
replicas
constraints
restrict

Answer 368

resources

Question 369

Which command can be used to deploy the STACKDEMO stack from a compose file? Select all the right answers.

docker stack deploy –compose-file docker-compose.yml STACKDEMO
cat docker-compose.yml | docker stack deploy –compose-file - STACKDEMO
docker stack services –compose-file docker-compose.yml STACKDEMO
docker stack ps –compose-file docker-compose.yml STACKDEMO

Answer 369

docker stack deploy –compose-file docker-compose.yml STACKDEMO
cat docker-compose.yml | docker stack deploy –compose-file - STACKDEMO

Question 370

Refer to the below Docker stack file and answer the following questions:

version: 3
services:
  redis:
    image: "redis:alpine"
    deploy:
      replicas: 3
  db:
    image: postgres:9.4
    deploy:
      replicas: 1
      placement:
        constraints:
          - "node.role==manager"
  web:
    image: webapp
    deploy:
      replicas: 5
    healthcheck:
      test: ["CMD", "curl", "-f", "http://localhost"]
      interval: 30s
      timeout: 5s
      retries: 5
      start_period: 120s

How many containers would be created in total for all services together?

3
9
5
1

Answer 370

9

Question 371

version: 3
services:
  redis:
    image: "redis:alpine"
    deploy:
      replicas: 3
  db:
    image: postgres:9.4
    deploy:
      replicas: 1
      placement:
        constraints:
          - "node.role==manager"
  web:
    image: webapp
    deploy:
      replicas: 5
    healthcheck:
      test: ["CMD", "curl", "-f", "http://localhost"]
      interval: 30s
      timeout: 5s
      retries: 5
      start_period: 120s

Which of the below statements are true?

The redis container will always be deployed on the manager node
The postgres container will only be deployed on the manager node
The web container may be deployed on any node – manager or worker
The redis container will not be deployed on the manager node

Answer 371

The postgres container will only be deployed on the manager node
The web container may be deployed on any node – manager or worker

Question 372

Refer to the below Docker stack file and answer the following questions:

version: 3
services:
  redis:
    image: "redis:alpine"
    deploy:
      replicas: 3
  db:
    image: postgres:9.4
    deploy:
      replicas: 1
      placement:
        constraints:
          - "node.role==manager"
  web:
    image: webapp
    deploy:
      replicas: 5
    healthcheck:
      test: ["CMD", "curl", "-f", "http://localhost"]
      interval: 30s
      timeout: 5s
      retries: 5
      start_period: 120s

The health check on the web service is configured to run at an interval of every 30 seconds. What would happen if the webserver takes 45 seconds to boot up the first time?

The web server container will be killed and restarted after 30 seconds
The health checks only start after 2 minutes, so the webserver has sufficient time to boot up
The health checks runs every 5 seconds and will mark the container as failed after 5 attempts
The web service will go into an infinite loop

Answer 372

The health checks only start after 2 minutes, so the web server has sufficient time to boot up

Question 373

version: 3
services:
  redis:
    image: "redis:alpine"
    deploy:
      replicas: 3
  db:
    image: postgres:9.4
    deploy:
      replicas: 1
      placement:
        constraints:
          - "node.role==manager"
  web:
    image: webapp
    deploy:
      replicas: 5
    healthcheck:
      test: ["CMD", "curl", "-f", "http://localhost"]
      interval: 30s
      timeout: 5s
      retries: 5
      start_period: 120s

What does the timeout value in the health check stand for?

The time after the container starts and before the first health check starts
The time between each health check trigger
The time the health check test – in this case, curl – waits to receive a successful response
The number of times a check is performed before marking the container failed

Answer 373

The time the health check test – in this case curl – waits to receive a successful response

Question 374

version: 3
services:
  redis:
    image: "redis:alpine"
    deploy:
      replicas: 3
  db:
    image: postgres:9.4
    deploy:
      replicas: 1
      placement:
        constraints:
          - "node.role==manager"
  web:
    image: webapp
    deploy:
      replicas: 5
    healthcheck:
      test: ["CMD", "curl", "-f", "http://localhost"]
      interval: 30s
      timeout: 5s
      retries: 5
      start_period: 120s

What do the retries value in the health check configuration stand for?

The time after the container starts and before the first health check starts
The time between each health check trigger
The time the health check test – in this case, curl – waits to receive a successful response
The number of times a check is performed before marking the container failed
The number of times the container restarts after the health check fails

Answer 374

The number of times a check is performed before marking the container failed

Question 375

You could restrict the resources assigned to a service using the … property in the docker stack.

resources
replicas
constrains
restrict

Answer 375

resources

Question 376

Which command can be used to promote worker2 to a manager node? Select the right answer.

docker promote node worker2
docker node promote worker2
docker swarm node promote worker2
docker swarm promote node worker2

Answer 376

docker node promote worker2

Question 377

The communication between the nodes in the swarm cluster are not secured by default.

True
False

Answer 377

False

“Secure by default: Each node in the swarm enforces TLS mutual authentication and encryption to secure communications between itself and all other nodes.”

Question 378

Which command can be used to run an instance on swarm?

docker container run -d cloud
docker container create cloud
docker service create cloud
docker swarm service create cloud

Answer 378

docker service create cloud

Question 379

The … network connects multiple Docker daemons together and enables swarm services to communicate with each other.

host
bridge
overlay
none

Answer 379

overlay

Question 380

Create a swarm service redisapp with image redis and expose port 8080 on host to port 6379 in container.

docker container run –name=redisapp -p 8080:6379 redis
docker service create –name=redisapp -p 8080:6379 redis
docker service create –name=redisapp -p 8800:6379 –instances=3 redis
docker service create –replicas=3 redis

Answer 380

docker service create –name=redisapp -p 8080:6379 redis

Question 381

When you create a swarm service and do not connect it to a user-defined overlay network, it connects to the … network by default.

host
bridge
macvlan
ingress

Answer 381

ingress

Question 382

Map TCP port 80 in the container to port 9595 on the overlay network using the web-server image.

docker service create –publish published=9595,target=8080,protocol=tcp web-server
docker service create -p 80:9595/tcp web-server
docker service create –publish published=80,target=9595,protocol=udp web-server
docker service create -p 9595:80/tcp web-server

Answer 382

docker service create -p 9595:80/tcp web-server

Question 383

Which formula can be used to calculate the Quorum of N nodes?

N + 1
N+1 / 2
N / 2 +1
N /2 -1

Answer 383

N / 2 +1

Question 384

Create an overlay network that can also be connected by standalone containers that were not created as part of a swarm service.

docker network create –driver overlay –attachable aone-network

docker network create –driver overlay –subnet 10.15.0.0/16 aone-network

docker network create –driver overlay –opt encrypted aone-network

docker network create –driver overlay aone-network

Answer 384

docker network create –driver overlay –attachable aone-network

Question 385

Which Docker edition would we choose for obtaining the latest Docker Engine updates?

Docker Community Edition (CE)

Docker Developer Edition (DE)

Docker Enterprise Edition (EE)

Either Docker CE or Docker EE

Answer 385

Either Docker CE or Docker EE

“Docker CE and EE both get all the latest engine updates.”

Question 386

How would we go about backing up images in the Docker Trusted Registry (DTR)?

Run a docker pull on all of the images to transfer them to another host.

Execute a container using the dtr image with the backup-images command.

Create a backup of everything in the DTR image storage volume.

To back up images, back up the contents of the volume DTR used to store images.

Back up everything in /var/lib/docker/volumes.

Answer 386

Create a backup of everything in the DTR image storage volume.

“To back up images, back up the contents of the volume DTR used to store images.”

Question 387

What procedure should we follow to upgrade the Docker engine on an Ubuntu server?

Stop Docker, then install the packages with the newer version.

Remove all containers, stop Docker, and then install the newer version.

Install newer versions of the docker-ce and docker-ce-cli packages.

Stop Docker, remove the packages, and then reinstall the packages with a newer version.

Answer 387

Install newer versions of the docker-ce and docker-ce-cli packages.

“We must install newer versions of the packages in order to upgrade Docker.”

Question 388

Which of the following namespaces is not enabled by default?

uts

mnt

user

pid

Answer 388

user

“Docker requires special configuration in order to utilize user namespaces.”

Question 389

Sara wants to run a container using the busybox image, and she wants to pass a custom command to the container: echo Docker is great!. Which of the following commands will accomplish this?

docker run busybox echo Docker is great!

docker run busybox -cmd echo Docker is great!

docker run busybox [“echo”, “Docker is great!”]

docker run busybox -c echo Docker is great!

Answer 389

docker run busybox echo Docker is great!

This command will successfully execute the echo command in the container and print the message to the screen.

Question 390

Which of the following commands will run a busybox container and automatically delete it once it exits?

docker run –restart no busybox

docker run –rm –restart on-failure busybox

docker run –rm busybox

docker container rm busybox

Answer 390

docker run –rm busybox

The –rm flag instructs Docker to automatically delete the container once it exits.

Question 391

How would we create a new swarm cluster?

Start dockerd with the swarm=true flag.

Run docker cluster create.

Use a Docker compose file that defines a new cluster.

Run docker swarm init.

Answer 391

Run docker swarm init.

This command creates a new cluster and generates the current node inside the first Swarm manager.

Question 392

What is the difference between a manager and a worker in Docker swarm?

Managers control the cluster, while workers only execute workloads.

Managers never execute containers, workers do.

Managers handle networking, while workers handle containers.

Managers create new workers.

Answer 392

Managers control the cluster, while workers only execute workloads.

This describes the roles of managers and workers in a swarm.

Question 393

What does the EXPOSE directive do?

It documents ports intended for publishing at the time of running a container.

It makes a container’s port accessible externally.

It causes the container to listen on a port.

It automatically publishes ports when running a container.

Answer 393

“It documents ports intended for publishing at the time of running a container.”

The EXPOSE directive documents the ports that should be published when running a container from the image.

Question 394

Dave needs Docker to use a custom stop signal for halting his software. How can he build an image that will instruct Docker on which stop signal to use?

Dave should use the STOPSIGNAL directive.

Dave should locate the process and kill it manually.

Dave should use the STOP directive.

Dave should use the docker stop command.

Answer 394

Dave should use the STOPSIGNAL directive.

The STOPSIGNAL directive instructs Docker on which stop signal to use for halting a container process.

Question 395

Which Dockerfile directive would set up the base image that can serve as our starting point for establishing a new image?

BASE

ARG

FROM

START

Answer 395

FROM

The FROM directive sets the base image.

Question 396

Which of the following statements truly applies to the ENV directive?

It sets an environment variable on the host while the container is running.

It sets environment variables that are made available in subsequent build steps and to containers at the runtime.

It sets environment variables that are only visible at the container runtime.

It sets environment variables that are only visible during later build steps.

Answer 396

It sets environment variables that are made available in subsequent build steps and to containers at the runtime.

The ENV directive sets environment variables, and they’re visible during subsequent build steps and at the container runtime.

Question 397

How can we use multi-stage builds to generate small, efficient Docker images?

We can leverage the implementation of multi-stage builds, which will shorten the build processing times.

We can copy only specific files from previous stages so that we can keep the image as small as possible.

We can use separate build stages to delete files from the image.

We can build the image, and then run diagnostics on it in a separate stage to make it more efficient.

Answer 397

We can copy only specific files from previous stages so that we can keep the image as small as possible.

This is the primary use case for multi-stage builds.

Question 398

Which of the following are insecure ways to allow a Docker client to authenticate against a registry that uses a self-signed certificate? (Choose two)

We pass the –insecure-registry flag to the Docker daemon.

We add the registry to insecure-registries in /etc/docker/daemon.json.

We use the –skip-tls flag with docker login.

We add the self-signed certificate as a trusted registry certificate under /etc/docker/certs.d/.

Answer 398

We pass the –insecure-registry flag to the Docker daemon.

We add the registry to insecure-registries in /etc/docker/daemon.json.

^ These methods work and are insecure

Question 399

What is the term for a package containing all the software that’s needed to run a Docker container?

Kernel

Repository

Package

Image

An image contains the software that’s needed to run a Docker container.

Answer 399

• Image

“An image contains the software that’s needed to run a Docker container.”

Question 400

How is the ADD directive different from COPY? (Choose two)

The ADD directive can transfer a specific file between build stages.

The ADD directive can pull a file from an external URL.

The ADD directive can extract an archive into the image.

The ADD directive can transfer files over to a specific location inside the image

Answer 400

• The ADD directive can pull a file from an external URL.

“The ADD directive can pull from a URL while COPY cannot.”

• The ADD directive can extract an archive into the image.

“The ADD directive can extract archives while COPY cannot.”

Question 401

Describe what the RUN directive does.

The RUN directive executes a command on the host when building an image.

The RUN directive sets the default command for the image.

The RUN directive executes a command and commits the resulting changed files as a new layer in the image.

The RUN directive automatically runs a command when a new container gets created.

Answer 401

• The RUN directive executes a command and commits the resulting changed files as a new layer in the image.

“This accurately describes what RUN does.”

Question 402

What is the primary purpose of a Docker registry?

It provides a central location for storing and distributing images.

It builds images.

It stores and organizes Dockerfiles.

Scan images for vulnerabilities.

Answer 402

It provides a central location for storing and distributing images.

“This is what a Docker registry does.”

Question 403

What does the FROM directive do?

It indicates the build location of where the image is.

It pulls a file from an external source into the image.

It sets the working directory of containers ran using the image.

It sets a base image that can be used as a platform to begin builds.

Answer 403

It sets a base image that can be used as a platform to begin builds.

The FROM directive sets the base image.

Question 404

Which of the following is true about the creation of private Docker registries?

We need Docker Trusted Registry (DTR) present if we want to generate a private registry.

We can create our own registry by running a container with the registry image.

We cannot secure a private registry in Docker Community Edition (CE).

We need a Docker EE license to have our own private registry created.

Answer 404

We can create our own registry by running a container with the registry image.

“Running this image will create a private Docker registry.”

Question 405

Which of the following Kubernetes Node taint effects would evict existing Pods that do not tolerate the taint bearing that effect?

NoContainer

PreferNoSchedule

NoExecute

NoSchedule

Answer 405

NoExecute

“NoExecute evicts existing Pods from the Node.”

Question 406

In Kubernetes, Which of the following is needed in order to expand a PersistentVolumeClaim?

A Storage driver that supports volume expansion.

A StorageClass with allowVolumeExpansion=true.

A StorageClass with expandable=true.

A PersistentVolume with allowVolumeExpansion=true.

Answer 406

A StorageClass with allowVolumeExpansion=true.

“In order to expand a PersistentVolumeClaim, the StorageClass must have allowVolumeExpansion set to true.”

Question 407

Kelly has a Docker swarm cluster with –autolock enabled. One of her manager nodes has become locked, and she has lost the unlock key. Fortunately, there are still some swarm nodes that are not locked. How can she obtain the unlock key from one of the unlocked nodes?

Kelly can use the docker swarm key print command.

Kelly can use the docker swarm unlock-key command.

Kelly can look in the file located at /etc/docker/swarm/unlock.key.

Kelly can use the docker swarm unlock command.

Answer 407

Kelly can use the docker swarm unlock-key command.

“This command will retrieve the unlock key from a manager node that is currently not locked.”

Question 408

Where can you add volumes to a Pod in Kubernetes?

The Pod specification.

The Pod metadata.

The Pod template in a Service specification.

the Container Specification.

Answer 408

The Pod specification.

“Volumes are listed in the PodSpec.”

Question 409

We have some containerized software that needs to have a reference to the hostname of the node that the software is running on. Which of the following commands will let us pass the node hostname as an environment variable into each task in a service?

docker service create –env NODE_HOSTNAME=”{{.Node.Hostname}}” nginx

docker service create –pass-node-hostname=true nginx

docker service create -e NODE_HOSTNAME nginx

docker service create –env NODE_HOSTNAME=”{{Hostname}}” nginx

Answer 409

docker service create –env NODE_HOSTNAME=”{{.Node.Hostname}}” nginx

“This command will create an environment variable in each task that contains the node hostname.”

Question 410

How would we back up the metadata for Docker Swarm?

We can run the swarm image with the backup command.

We can back up the contents of /etc/docker/swarm.

We can back up the contents of /usr/local/swarm.

While the Docker daemon stops, we can back up the contents of /var/lib/docker/swarm on a Swarm manager.

Answer 410

While the Docker daemon stops, we can back up the contents of /var/lib/docker/swarm on a Swarm manager.

“We can back up Docker Swarm metadata by backing up the contents of this directory.”

Question 411

What should we use if we need to run multiple copies of a single image in a swarm?

We should use a task.

We should use a service.

We should use a stack.

We should run the docker-compose command.

Answer 411

We should use a service.

“Services are used to run multiple replicas that use the same image.”

Question 412

Which of the following commands will evenly spread out tasks based upon the values of a node label?

docker service create –constraint spread=node.labels.availability_zone nginx

docker service create –placement-pref spread=node.labels.availability_zone nginx

docker service create –placement-pref spread nginx

docker service create –placement-pref even-spread=node.labels.availability_zone nginx

Answer 412

docker service create –placement-pref spread=node.labels.availability_zone nginx

“This command will evenly spread out tasks based upon the values of the availability_zone label.”

Question 413

You have a web application frontend that will need to be accessed by users, and a backend database that will be accessed by the frontend Pods. Both of these components are running within your Kubernetes cluster. Which Service types should you use to expose the web frontend and the backend database, respectively?

NodePort, ClusterIP

ClusterIp for both.

NodePort for both.

ClusterIP, NodePort

Answer 413

NodePort, ClusterIP

You can use a NodePort Service to allow users to access the frontend, while a ClusterIP Service exposes the backend database to other pods within the cluster.

Question 414

Sally wants to prevent Docker Swarm encryption keys from being stored insecurely on her swarm managers. How can she tackle enforcing a lock on the swarm cluster?

The auto-lock feature must be turned on when the cluster is initialized and cannot be enabled after the fact.

Sally cannot do this because Docker does not offer this functionality.

Sally can use the –autolock=true flag with the docker swarm update command.

Sally can locate the critical files after the installation and delete them.

Answer 414

Sally can use the –autolock=true flag with the docker swarm update command.

“This command will turn on –autolock, ensuring that managers will be automatically locked whenever the Docker daemon restarts.”

Question 415

How would we rotate a docker swarm unlock-key and ensure that all nodes receive the new key?

We can use the docker swarm unlock command.

We would run the docker swarm unlock-key –rotate command on one manager node.

We would run the docker swarm unlock-key –rotate command on all manager nodes.

We would generate a new key and save it in a file located at /etc/docker/swarm/unlock.key.

Answer 415

We would run the docker swarm unlock-key –rotate command on one manager node.

This command will automatically rotate the key and handle all orchestration between nodes.

Question 416

Which of the following scenarios would still allow the quorum to complete maintenance in a swarm cluster? (Choose two)

A 3-node cluster with 2 nodes down.

A 7-node cluster with 3 nodes down.

A 4-node cluster with 2 nodes down.

A 3-node cluster with 1 node down.

Answer 416

A 7-node cluster with 3 nodes down.

“More than half of the nodes are still up, so the quorum is maintained in this scenario.”

A 3-node cluster with 1 node down.

“More than half of the nodes are still up, so the quorum is maintained in this scenario.”

Question 417

Which of the following commands will allow us to add a label to a Docker Swarm node?

docker node update –label-add

docker node tag

docker node update –labels

docker label add

Answer 417

docker node update –label-add

“This command will add a label to the node.”

Question 418

Which devicemapper mode should we use for a production environment?

loop-lvm

direct-lvm

block storage

overlay2

Answer 418

direct-lvm

“We should use direct-lvm mode in a production environment.”

Question 419

Which of the following commands may result in the creation of a new named volume?

docker run -v my-vol:/tmp nginx

docker run -v /my-vol:/tmp nginx

docker run -v /my-vol:/tmp:create nginx

docker run –mount source=/my-vol,destination=/tmp nginx

Answer 419

docker run -v my-vol:/tmp nginx

“This command will create a new volume called my-vol if one does not already exist under that name.”

Question 420

Which of the following is true of filesystem storage models? (Choose two)

They are efficient with write-heavy workloads.

They store data in regular files on the host machine.

They use an external, object-based store.

They are used by overlay2 and aufs.

The overlay2 and aufs storage drivers both use filesystem storage models.

Answer 420

• They store data in regular files on the host machine.

“Filesystem storage models simulate a file system and store the data in regular files onto the host machine.”

• They are used by overlay2 and aufs.

“The overlay2 and aufs storage drivers both use filesystem storage models.”

Question 421

Which of the following commands would we use to retrieve a list of volumes on the current machine?

docker volume ps

docker volume rm

docker volume ls

docker volume inspect

Answer 421

docker volume ls

“This command will return a list of volumes on the current machine.”

Question 422

Which of the following commands can we use to locate the actual files that store a container’s internal data?

docker volume ls

docker container inspect

docker image inspect

docker container volume ls

Answer 422

docker container inspect

“This command will return the container metadata, including the location of its data on the host.”

Question 423

When creating a container, how would we specify that the container should be attached to an existing network called my-network?

We can use docker run –network-alias web nginx.

We can use docker run -n my-network nginx.

We can use docker run –attach my-network nginx.

We can use docker run –network my-network nginx.

Answer 423

We can use docker run –network my-network nginx.

“This command will attach the container to an existing network called my-network.”

Question 424

Which component of the Docker Container Networking Model (CNM) is responsible for allocating IP addresses within Docker networks?

A Docker Swarm manager is responsible.

The Docker network is responsible.

The network driver is responsible.

The IP Address Management (IPAM) Driver is responsible.

Answer 424

The IP Address Management (IPAM) Driver is responsible.

“The IPAM driver handles IP allocation”

Question 425

When creating an overlay network, what flag can we use to allow containers to attach to the network after it is created?

–attachable

–network-driver attachable

–open true

–attach=true

Answer 425

–attachable

“After the creation of the overlay network, the –attachable flag will allow containers to attach to the network.”

Question 426

Which of the following commands will publish a service’s port, but only on nodes that are running a task for that service?

docker service create -p mode=ingress,published=8082,target=80 nginx

docker service create -p 8080:80 nginx

docker service create -p 8080:80 –mode host nginx

docker service create -p mode=host,published=8082,target=80 nginx

Answer 426

docker service create -p mode=host,published=8082,target=80 nginx

“Host publishing mode only publishes ports on nodes that are running a task for the service.”

Question 427

Which of the following tasks can we perform to set a custom DNS server for a container?

We can use the –nameserver flag with docker run.

We can use the –dns flag with docker run.

We can set “dns” in /etc/docker/daemon.json.

We can use the –dns-override flag with docker run.

Answer 427

We can use the –dns flag with docker run.

“This method would allow us to set a custom DNS server for the container.”

Question 428

Which of the following is a valid method that we can use for setting the default DNS server for all containers on a host?

We can use docker config set dns.

We can use the –dns flag with docker run.

We can set “dns” in /etc/docker/daemon.json.

We can edit the /etc/hosts file on the host.

Answer 428

We can set “dns” in /etc/docker/daemon.json.

“This method will set the default DNS for all containers on the host.”

Question 429

What component of the Docker Container Networking Model (CNM) refers to a collection of endpoints that can communicate with one another?

Network

Network device

IP Address Management (IPAM) Driver

Sandbox

Answer 429

Network

A network is a bridge that allows endpoints plus containers to communicate with one another.

Question 430

Which of the following is true of a service that has a port published in ingress mode?

The service will listen on all nodes on the cluster.

The service will only listen on a manager.

The service will only listen on worker nodes that are running the service’s tasks and manager nodes.

The service will only listen on nodes that are running tasks associated with the service.

Answer 430

The service will listen on all nodes on the cluster.

“With ingress mode services listen on all nodes in the cluster.”

Question 431

Which of the following statements about grants in the Universal Control Plane (UCP) is accurate?

Each grant refers to one or more roles.

A grant provides permissions concerning precisely one object.

Grants can give permissions to a user, team, or organization.

Grants give permissions to a subject, which consists of a user, team, or organization.

For each user, only one grant may be assigned.

Answer 431

Grants can give permissions to a user, team, or organization.

“Grants give permissions to a subject, which consists of a user, team, or organization.”

Question 432

Tracy has a Docker Trusted Registry (DTR), and her development team has been mistakenly overwriting images in a repository by pushing a different image with an existing tag. How can she prevent this from happening?

Tracy can remove the team’s access to the registry.

Tracy can make the repository private.

Tracy can back up the registry.

Tracy can mark the repository as immutable.

Answer 432

Tracy can mark the repository as immutable.

“Marking the repository as immutable will prevent her team from overwriting existing tags.”

Question 433

What is the name of Docker feature that enables us to sign images and verify image signatures before running them?

Docker Image Trust

Docker registry

Docker Content Trust

Docker Trusted Registry

Answer 433

Docker Content Trust

“Docker Content Trust allows us to sign images and verify signatures before running them.”

Question 434

How can we provide custom certificates to the Universal Control Plane (UCP) and Docker Trusted Registry (DTR)?

We must supply the certificates during the UCP and DTR installation process.

We can push new certificates via the UCP web API.

We can upload certificates via the UCP and DTR web UIs.

docker ucp config –cert

Answer 434

We can upload certificates via the UCP and DTR web UIs.

“We can upload certificates in the administrative settings section for both UCP and DTR.”

Question 435

How can you enable Docker Content Trust (DCT) in Docker Community Edition (CE)?

Set the CONTENT_TRUST environment variable to 1.

Set the DOCKER_CONTENT_TRUST environment variable to 1.

Set “content-trust”: true in /etc/docker/daemon.json.

Pass the –content-trust flag to dockerd.

Answer 435

Set the DOCKER_CONTENT_TRUST environment variable to 1.

Setting this environment variable to 1 will enable DCT.

Question 436

Which command allows us to create an encrypted overlay network?

docker network create –opt encrypted my-net

docker network create –opt encrypted –driver overlay my-net

docker network create –encrypted –driver overlay my-net

docker network create –secure –driver overlay my-net

Answer 436

docker network create –opt encrypted –driver overlay my-net

“This command will create an encrypted overlay network.”

Question 437

What is an easy way to configure a client to communicate with Universal Control Plane (UCP) using client certificates?

We can execute the docker login command.

docker ucp login

We can log into UCP via a browser.

We can download and use a client bundle.

Answer 437

We can download and use a client bundle.

“Client bundles provide client certificates for authenticating with UCP.”

Question 438

Given Docker’s architecture and built-in security features, which of the following security scenarios should we be concerned about the most?

If an attacker gains control of a container, they could use it to affect other containers on the same host directly.

An attacker may intercept swarm-level traffic between swarm nodes and obtain sensitive information from the data.

If an attacker gains access to the Docker daemon, they could use it to execute commands as root on the host.

An attacker could set up a false machine under their control and join it to the swarm cluster to steal sensitive data, causing containers with sensitive data to execute on a fake device.

Answer 438

If an attacker gains access to the Docker daemon, they could use it to execute commands as root on the host.

The Docker daemon must run as root, so it is essential to ensure that it’s being protected and has limited access to it.

Question 439

Which statements best describes Docker Enterprise?

Docker Enterprise provides a consistent and secure end-to-end application pipeline, choice of tools and languages, and globally consistent Kubernetes environments that run in any cloud.

Docker Enterprise enables deploying highly available workloads using Docker Swarm only.

Docker Enterprise automates many of the tasks that orchestration requires, like provisioning pods, containers, and cluster resources.

Self-healing components ensure that Docker Enterprise clusters remain highly available.

Answer 439

Docker Enterprise provides a consistent and secure end-to-end application pipeline, choice of tools and languages, and globally consistent Kubernetes environments that run in any cloud.

Docker Enterprise automates many of the tasks that orchestration requires, like provisioning pods, containers, and cluster resources.

Self-healing components ensure that Docker Enterprise clusters remain highly available.

Question 440

Which of the below statements are true?

Docker CE or Docker Community Edition is the open-source and free version of Docker.

Docker CE needs a license key (or) file to activate it.

Both Docker Community Edition and Docker Enterprise Edition have the same core features and functions. Docker Enterprise Edition comes with additional support for IT teams to build, share and run business-critical applications at scale.

The only difference between Docker CE and Docker EE is that Docker EE comes with a dedicated support team

Answer 440

Docker CE or Docker Community Edition is the open-source and free version of Docker.

Both Docker Community Edition and Docker Enterprise Edition have the same core features and functions. Docker Enterprise Edition comes with additional support for IT teams to build, share and run business-critical applications at scale.

Question 441

Docker Engine Enterprise is a hardened and secure version of Docker Engine.

True
False

Answer 441

True

Question 442

Which of the following are the features of Docker Enterprise Edition?

 Security & Access Control
 Universal Control Plane & Trusted Registry
 Source Code Management
 Docker Swarm Service
 Kubernetes Service

Answer 442

Security & Access Control

Universal Control Plane & Trusted Registry

Docker Swarm Service

Kubernetes Service

Question 443

Docker Enterprise cluster can only be provisioned on public cloud platforms.

True
False

Answer 443

False

Question 444

You can download your Docker EE license by navigating to the “My Content” page on Docker Store.

True
False

Answer 444

True

Question 445

…. is the enterprise-grade cluster management platform from Docker. You install it on-premises or in your virtual private cloud, and it helps you manage your Docker cluster and applications through a single interface.

Universal Control Plane (UCP)
Docker Enterprise Edition
Docker Community Edition
Docker Trusted Registry (DTR)

Answer 445

Universal Control Plane (UCP)

Question 446

… is a combination of multiple enterprise-grade tool sets which include Docker Engine Enterprise as well as container orchestration and registry tools.

Universal Control Plane (UCP)
Docker Enterprise Edition
Docker Community Edition
Docker Trusted Registry (DTR)

Answer 446

Docker Enterprise Edition

Question 447

… is the enterprise-grade image storage solution from Docker. You install it behind your firewall so that you can securely store and manage the Docker images you use in your applications.

Universal Control Plane (UCP)
Docker Enterprise Edition
Docker Community Edition
Docker Trusted Registry (DTR)

Answer 447

Docker Trusted Registry (DTR)

Question 448

Docker EE license subscription includes …. product.

Universal Control Plane (UCP)

Docker Trusted Registry (DTR)

Docker Engine – Enterprise with enterprise-grade support

Docker Engine – Community Edition

Answer 448

Universal Control Plane (UCP)

Docker Trusted Registry (DTR)

Docker Engine – Enterprise with enterprise-grade support

Question 449

…. is one of the system requirements for UCP.

The nodes must be Linux Kernel version 3.10 or higher

Each node must be configured with a static ip address

User namespaces should not be configured on any node

all nodes must have Docker Engine Enterprise installed

Answer 449

The nodes must be Linux Kernel version 3.10 or higher

Each node must be configured with a static ip address

User namespaces should not be configured on any node

all nodes must have Docker Engine Enterprise installed

Question 450

User namespaces should not be configured on any node as they are not currently supported in UCP.

True
False

Answer 450

True

Question 451

With …, you can manage all of the computing resources you have available, like nodes, volumes, and networks from a centralized place.

Universal Control Plane (UCP)

Docker Enterprise Edition

Docker Community Edition

Docker Trusted Registry (DTR)

Answer 451

Universal Control Plane (UCP)

Question 452

DTR is highly available through the use of multiple replicas of all containers and metadata such that if a machine fails, DTR continues to operate and can be repaired.

True
False

Answer 452

True

Question 453

Docker enterprise is the only platform that supports both Docker swarm and Kubernetes on the same cluster.

True
False

Answer 453

True

Question 454

Which command can be used to verify the installed docker is a CE or EE?

docker container ls
docker version
docker –version
None of the above

Answer 454

docker version

Question 455

Which of the following need to be installed in order to provision the Docker EE infrastructure?

Docker Enterprise Engine should be installed on every node inside your Docker EE setup

A MongoDB database should be pre-provisioned prior to installing Docker EE

Install the Universal Control Plane (UCP)

Install the Docker Trusted Registry (DTR)

Answer 455

Docker Enterprise Engine should be installed on every node inside your Docker EE setup

Install the Universal Control Plane (UCP)

Install the Docker Trusted Registry (DTR)

Question 456

Which of the following are the major components of Docker Engine – Enterprise?

A server which is a type of long-running program called a daemon process (the dockerd command).

A REST API which specifies interfaces that programs can use to talk to the daemon and instruct it what to do.
A command-line interface (CLI) client (the docker command).

Answer 456

A server which is a type of long-running program called a daemon process (the dockerd command).

A REST API which specifies interfaces that programs can use to talk to the daemon and instruct it what to do.

A command-line interface (CLI) client (the docker command).

Question 457

Docker Engine – Enterprise can only be installed on linux distros.

True
False

Answer 457

False

Question 458

To install Docker Enterprise, you will need the URL of the Docker Enterprise repository associated with your trial or subscription.

True
False

Answer 458

True

Question 459

Which command can be used to start the docker ee service on a systemctl configured system?

sudo systemctl start docker-ee
sudo systemctl start docker
sudo systemctl docker start
sudo systemctl docker-ee start

Answer 459

sudo systemctl start docker

Question 460

What is the command to show the installed version of “Docker Enterprise” Server and Client?

docker version
docker –version
docker -V
docker -v

Answer 460

docker version

Question 461

Which of the below statements best describe the Universal Control Plane (UCP)?

UCP manages your Docker cluster and applications through a single interface.

Universal Control Plane (UCP) is the enterprise-grade cluster management solution from Docker.

UCP stores and manages images used by applications

UCP has its own built-in authentication mechanism and integrates with LDAP and AD services.

Answer 461

Universal Control Plane (UCP) is the enterprise-grade cluster management solution from Docker.

UCP has its own built-in authentication mechanism and integrates with LDAP and AD services.

Question 462

UCP provides a simple and easy-to-use GUI to manage your applications.

True
False

Answer 462

True

Question 463

Which of the following features does UCP provide?

Centralized Cluster Management

Deploy, manage and monitor workload

Built-in security and access control

Issue Tracker

Source Code Management

Answer 463

Centralized Cluster Management

Deploy, manage and monitor workload

Built-in security and access control

Question 464

What are the minimum hardware requirements to install UCP?

4GB RAM, 2vCPUs and 10GB disk space for the /var partition for manager nodes, 2GB RAM and 500MB disk space for the /var partition for worker nodes

8GB RAM, 2vCPUs and 10GB disk space for the /var partition for manager nodes, 4GB RAM and 500MB disk space for the /var partition for worker nodes

8GB RAM, 2vCPUs and 10GB disk space for the /var/lib/docker partition for manager nodes, 4GB RAM and 500MB disk space for the /var/lib/docker partition for worker nodes

4GB RAM, 2vCPUs and 10GB disk space for the /var/lib/docker partition for manager nodes, 2GB RAM and 500MB disk space for the /var/lib/docker partition for worker nodes

Answer 464

8GB RAM, 2vCPUs, and 10GB disk space for the /var partition for manager nodes

4GB RAM and 500MB disk space for the /var partition for worker nodes

Question 465

Which of the following are the prerequisites to install UCP for linux?

The nodes must be Linux Kernel version 3.10 or higher.

Each node must be configured with a static ip address.

Ensure they are configured with an NTP server to sync time.

User namespaces should be configured on every node.

All nodes must have Docker Engine Enterprise installed.

Answer 465

The nodes must be Linux Kernel version 3.10 or higher.

Each node must be configured with a static ip address.

Ensure they are configured with an NTP server to sync time.

All nodes must have Docker Engine Enterprise installed.

Question 466

Which of the following are the components deployed on the manager node by UCP?

 ucp-controller
 ucp-metric
 ucp-proxy
 ucp-auth-api
 ucp-agent

Answer 466

ucp-controller

ucp-auth-api

Question 467

Which of the following are the components deployed by UCP on worker nodes?

ucp-agent
ucp-metric
ucp-proxy
ucp-auth-api

Answer 467

ucp-agent

ucp-proxy

Question 468

Which of the following steps are required to add a worker node to a UCP cluster?

Make sure Docker EE is up and running and Pull the UCP image from the registry

Set the Admin Username and Password for UCP Console

Login to the Browser and provide the downloaded Docker EE License

Add more managers and workers as per requirement

Answer 468

Make sure Docker EE is up and running and Pull the UCP image from the registry

Set the Admin Username and Password for UCP Console

Login to the Browser and provide the downloaded Docker EE License

Add more managers and workers as per requirement

Question 469

UCP works with Docker swarm under the hoods.

True
False

Answer 469

True

Question 470

When a new node is added to the cluster the ucp-agent is deployed there and it automatically configures the node to work with UCP.

True
False

Answer 470

True

Question 471

UCP has its own built-in authentication mechanism and integrates with LDAP and AD services.

True
False

Answer 471

True

Question 472

When UCP is deployed it creates a replicated service called ucpagent.

True
False

Answer 472

False

Question 473

When a new node is added to the cluster, an ucp-agent is deployed there.

True
False

Answer 473

True

Question 474

Which component is responsible to serve the UCP components such as the web ui, the authentication api,metrics server, proxy and data stores used by UCP in the form of containers?

UCP Agent
Docker Enterprise Edition
Docker Community Edition
Docker Trusted Registry (DTR)

Answer 474

UCP Agent

Question 475

We can interact with UCP from the GUI only.

True
False

Answer 475

False

Question 476

One of the prerequisites to install the UCP is make sure that the Docker CE is up and running.

True
False

Answer 476

False

Question 477

Which of the following steps are required to add a worker node?

Provision a node and Install Docker enterprise engine on it.

Run the <code>docker swarm join</code> command to join the new node to the cluster.

Deploy an instance of the ucp-agent on the new node.

ucp-agent then installs the necessary components on the worker node.

Answer 477

Provision a node and Install Docker enterprise engine on it.

Run the <code>docker swarm join</code> command to join the new node to the cluster.

ucp-agent then installs the necessary components on the worker node.

Question 478

The ucp-agent installs the necessary components on the worker node automatically after a new node joins the cluster.

True
False

Answer 478

True

Question 479

ucp-agent is configured as a global service.

True
False

Answer 479

True

Question 480

Docker Trusted Private Registry stores Docker Images in a highly secure manner with additional features like Image signing, and Image scans etc.

True
False

Answer 480

True

Question 481

Which of the following statements best describe Docker Trusted Registry (DTR)?

Docker Trusted Registry (DTR) is Mirantis’s enterprise-grade image storage solution.

Images stored on DTR can only be accessed from within the Docker EE Cluster

DTR provides a secure environment on which users can store and manage Docker images.

DTR should be installed only on a worker node that is managed by UCP

Answer 481

Docker Trusted Registry (DTR) is Mirantis’s enterprise-grade image storage solution.

DTR provides a secure environment on which users can store and manage Docker images.

DTR should be installed only on a worker node that is managed by UCP

Question 482

What are the features of Docker Trusted Registry (DTR)?

Built-in Access Control

Image and Job Management

Automated image builds

Security Scanning

Dockerfile management in SCM

Image Signing

Answer 482

Built-in Access Control

Image and Job Management

Security Scanning

Image Signing

Question 483

What is a recommended approach to deploying DTR?

Deploy a single instance of DTR.

Deploy at least 2 instances of DTR to support high availability.

Deploy at least 3 instances of DTR to support high availability.

Answer 483

Deploy at least 3 instances of DTR to support high availability.

Question 484

DTR is able to reduce the bandwidth used when pulling Docker images by caching images closer to users.

True
False

Answer 484

True

Question 485

Docker Trusted Registry (DTR) is a containerized application that runs on a Docker Universal Control Plane cluster.

True
False

Answer 485

True

Question 486

To install DTR, all nodes must _______ and ____________.

Be a worker node managed by UCP

Be a manager node managed by UCP

Have a fixed hostname

Have at least 200 GB of disk space

Answer 486

Be a worker node managed by UCP

Have a fixed hostname

Question 487

What are the minimum hardware requirements to install DTR?

4GB RAM, 2vCPUs, and 200GB of free disk space.

8GB RAM, 2vCPUs, and 200GB of free disk space.

16GB RAM, 2vCPUs, and 10GB of free disk space.

8GB RAM, 2vCPUs, and 10GB of free disk space.

Answer 487

16GB RAM, 2vCPUs, and 10GB of free disk space.

Question 488

What are the recommended hardware requirements to install DTR?

16GB RAM, 2vCPUs and 100GB of free disk space.

16GB RAM, 4vCPUs and 25-100GB of free disk space.

8GB RAM, 4vCPUs and 25-100GB of free disk space.

8GB RAM, 2vCPUs and 100GB of free disk space.

Answer 488

16GB RAM, 4vCPUs, and 25-100GB of free disk space.

Question 489

DTR and UCP must be installed on the same node.

True
False

Answer 489

False

Question 490

DTR also supports RBAC for access control.

True
False

Answer 490

True

Question 491

… is a private image registry/repository that can be deployed within your organization to store images securely.

DTR

UCP

UCP Agent

None of the above

Answer 491

DTR

Question 492

DTR can only be installed on-premises, and not on virtual private cloud.

True
False

Answer 492

False

Question 493

DTR has a web user interface that allows authorized users in your organization to browse Docker images and review repository events.

True
False

Answer 493

True

Question 494

Which image is used to deploy the dtr?

dtr
docker/dtr
ucp
docker/ucp

Answer 494

docker/dtr

Question 495

What is the type and the name of the network of the DTR deployment?

overlay/dtr
overlay/dtr-ol
bridge/dtr
bridge/dtr-ol

Answer 495

overlay/dtr-ol

Question 496

By default, the docker registry stores the images you push to it in an NFS shared storage.

True
False

Answer 496

False

Question 497

You can interact with the UCP either through the UCP GUI Console or through the CLI.

True
False

Answer 497

True

Question 498

Which of the following statements are true about deploying workload via GUI on UCP Cluster?

The Docker swarm section in the UI helps create swam services by specifying the image details, scheduling, network, environment, resource, and logging configuration.

UCP only supports deploying workloads on Docker Swarm

UCP only supports deploying workloads on External Kubernetes Clusters

The Kubernetes section in the UI helps create Kubernetes objects such as PODs, services, ingress, controllers such as replicasets, deployments, daemonsets, statefulsets, job or cron jobs as well as service accounts or storage.

Answer 498

The Docker swarm section in the UI helps create swam services by specifying the image details, scheduling, network, environment, resource, and logging configuration.

The Kubernetes section in the UI helps create Kubernetes objects such as PODs, services, ingress, controllers such as replicasets, deployments, daemonsets, statefulsets, job or cron jobs as well as service accounts or storage.

Question 499

Which of the following statements are true about deploying workload via CLI on UCP Cluster?

With CLI you may use the docker command-line interface to interact with the UCP cluster.

CLI access doesn’t require authentication to the UCP Cluster.

CLI access requires authentication to the UCP Cluster.

Download the certificate from UCP Console and copy this over to the server from where you’d like to access and extract it to a path.

Answer 499

With CLI you may use the docker command-line interface to interact with the UCP cluster.

CLI access requires authentication to the UCP Cluster.

Download the certificate from UCP Console and copy this over to the server from where you’d like to access and extract it to a path.

Question 500

You can interact with the UCP through the CLI.

True
False

Answer 500

True