Infrastructure and automation

Question 1

What are three benefits of Infrastructure automation

Answer 1

Speed
Repeatability
The ability to work at scale, with reduced risk

Question 2

What is an imperative procedure

Answer 2

an ordered sequence of commands aimed at achieving a goal. The sequence may include flow-control, conditions, functional structure, classes, and more.

Question 3

What is provisioning

Answer 3

refers to obtaining compute, storage, and network infrastructure (real or virtual), enabling communications, putting it into service, and making it ready for use by operators and developers (e.g., by installing an operating system, machine-level metrics, ssh keys, and the lowest level of operations tooling).

Question 4

What is configuration

Answer 4

means installing base applications and services and performing the operations, tasks, and tests required to prepare a low-level platform to deploy applications or a higher-level platform.

Question 5

What does Deployment mean

Answer 5

involves building, arranging, integrating, and preparing multi-component applications (such as database clusters) or higher-level platforms (like Kubernetes clusters), often across multiple nodes.

Question 6

What is Orchestration

Answer 6

may refer to several things. When meant concretely, it usually refers to user-built or platform-inherent automation aimed at managing workload lifecycles and reacting dynamically to changing conditions (e.g., by autoscaling or self-healing), particularly in container environments. When meant abstractly, it may refer simply to processes or workflows that link automation tasks to deliver business benefits, like self-service.

Question 7

What is provisioning

Answer 7

refers to obtaining compute, storage, and network infrastructure (real or virtual), enabling communications, putting it into service, and making it ready for use by operators and developers (e.g., by installing an operating system, machine-level metrics, ssh keys, and the lowest level of operations tooling)

Question 8

What is Configuration

Answer 8

means installing base applications and services and performing the operations, tasks, and tests required to prepare a low-level platform to deploy applications or a higher-level platform.

Question 9

What is deployment

Answer 9

involves building, arranging, integrating, and preparing multi-component applications (such as database clusters) or higher-level platforms (like Kubernetes clusters), often across multiple nodes.

Question 10

What is Orchestration

Answer 10

may refer to several things. When meant concretely, it usually refers to user-built or platform-inherent automation aimed at managing workload lifecycles and reacting dynamically to changing conditions (e.g., by autoscaling or self-healing), particularly in container environments. When meant abstractly, it may refer simply to processes or workflows that link automation tasks to deliver business benefits, like self-service.

Question 11

Describe a stateless / No state to store application

Answer 11

This app requires only atomic/synchronous interactions between client and server: each request from client to server returns a result wholly independent of prior and subsequent requests. An example of this application is a public web server that returns an HTML page, image, or other data on request from a browser. The application can be scaled by duplicating servers and data behind a simple load balancer.

Question 12

Describe Stateless / State stored on database app

Answer 12

User state is stored in a database accessible to any webserver in the middle tier. An example of this application is a web server that needs to be aware of the correspondence between a user ID and user cookie. New webservers and copies of the website can be added freely without disrupting user sessions in progress and without requiring that each request from a given user be routed to the specific server that maintains their session.

Question 13

Describe Stateful /State stored on server app

Answer 13

A record of user state must be maintained across a series of transactions. An example of this application is a website that requires authentication: the app isn’t allowed to serve pages to a user who is not logged in. User state is typically persisted by giving the client an identifying cookie that is returned to the server with each new request and used to match an ID stored there. This application can’t be scaled just by adding servers: if a logged-in user is routed to a server that hasn’t stored an ID matching the user’s cookie, that server won’t recognize them as being logged in, and will refuse their request.

Question 14

What is a playbook in Ansible

Answer 14

lists of tasks that automatically execute against hosts

Question 15

Explain the basic workflow for Ansible using playbooks

Answer 15

Engineers create Ansible playbooks in YAML that describe a workflow or the configuration of infrastructure.

Ansible playbooks are deployed to an Ansible control station.

When the control station runs the Ansible playbooks, they typically copy modules written
in Python to remote hosts.

Finally, Ansible runs the modules on the remote hosts to perform the work described in playbooks

Question 16

What is procedural automation

Answer 16

be used to capture and share corporate knowledge including best practices, and to minimize errors with resulting decrease in incidents, improved safety and higher throughput.

Question 17

What is the goal of any script

Answer 17

to achieve a desired state in a system regardless of starting conditions

Question 18

What is idempotency

Answer 18

means that the result of a successfully performed request is independent of the number of times it is executed

Question 19

What is the meaning of the idempotency principle “Look before you leap”

Answer 19

Also known as “If it ain’t broke, don’t fix it” and “First, do no harm”. Ensure the change you want to make hasn’t already been made. Doing nothing is almost always a better choice than doing something wrong and possibly unrecoverable.

Question 20

What is the meaning of the idempotency principle “Get to a known-good state, if possible, before making changes”

Answer 20

Secure a functional state before you go and change it

Question 21

What is the meaning of the idempotency principle “Test for idempotency “

Answer 21

Be scrupulous about building automation free from side effects

Question 22

What is the meaning of the idempotency principle “One bad apple spoils the bunch”

Answer 22

Only if all components of a procedure are known to be idempotent can the procedure as a whole be idempotent.

Question 23

What are the methods to configure a remote system

Answer 23

You can store scripts locally, transmit them to target machines with a shell utility like scp, then log into the remote machine using ssh and execute them.

You can pipe scripts to a remote machine using cat | ssh and execute them in sequence with other commands, capturing and returning results to your terminal, all in one command.

You can install a general-purpose secure file-transfer client like SFTP, then use that utility to connect to the remote machine, transfer, set appropriate permissions, then execute your script file.

You can store scripts on a webserver, log into the remote machine and retrieve them with wget, curl, or other utilities, or store the scripts in a Git repository — installing git on the remote machine, cloning the repo to it, checking out a branch, and executing the scripts found there.

You can install a full remote-operations solution like VNC or NoMachine locally, install its server on the target (this usually requires also installing a graphical desktop environment), transmit/copy and then execute scripts.

If your target devices are provisioned on a cloud framework (for example, UCS, AWS, Azure, GCP), there’s usually a way to inject a configuration script via the same CLI command or WebUI action that manifests the platform.

Question 24

What do automation tools do

Answer 24

“wrap” operating system utilities and API functions to simplify and standardize access

Question 25

What do automation tools enable

Answer 25

Compilation of variable definitions.
Server inventory as structured data and other details separate from generic code.
Orderly means to inject variable values into code, config file templates, and other destinations at runtime.

Question 26

What does ansible vault do

Answer 26

supports sophisticated functionality for encrypting sensitive files and variables, securely editing encrypted file contents, and more.

Question 27

Describe a stateful app

Answer 27

An app that saves important information in files or in a database on the local file.

Question 28

Describe a Stateless app

Answer 28

An app that persists its state to a separate database or that provides service that requires no memory of state between invocations.

Question 29

Describe a Stateless/ No state to store app

Answer 29

This app requires only atomic/synchronous interactions between client and server: each request from client to server returns a result wholly independent of prior and subsequent requests. An example of this application is a public web server that returns an HTML page, image, or other data on request from a browser. The application can be scaled by duplicating servers and data behind a simple load balancer.

Question 30

Describe a Stateless / State stored on database app

Answer 30

User state is stored in a database accessible to any webserver in the middle tier. An example of this application is a web server that needs to be aware of the correspondence between a user ID and user cookie. New webservers and copies of the website can be added freely without disrupting user sessions in progress and without requiring that each request from a given user be routed to the specific server that maintains their session.

Question 31

Describe a stateful / state stored on server app

Answer 31

A record of user state must be maintained across a series of transactions. An example of this application is a website that requires authentication: the app isn’t allowed to serve pages to a user who is not logged in. User state is typically persisted by giving the client an identifying cookie that is returned to the server with each new request and used to match an ID stored there. This application can’t be scaled just by adding servers: if a logged-in user is routed to a server that hasn’t stored an ID matching the user’s cookie, that server won’t recognize them as being logged in, and will refuse their request.

Question 32

What is Blue/green deployment

Answer 32

a method for reducing or eliminating downtime in production environments. It requires you to maintain two identical production environments (you don’t absolutely have to call them “Blue” and “Green” — people have been known to call them “Red” and “Black,” as well), and develop the new capability of quickly redirecting application traffic to one or the other (e.g., through ACI automation; load balancing; programmable DNS; or other means).

Question 33

What is canary testing

Answer 33

The migration between old and new deployments is performed on a customer-by-customer (or even user-by-user) basis, and migrations are made intentionally to reduce risk and improve the quality of feedback.

Question 34

What is Cisco DNA center

Answer 34

an open, extensible, software driven architecture for Catalyst 9000 and other IOSXE devices for enterprise network.

Question 35

What is application Centeric Infrastructure (ACI)

Answer 35

a comprehensive data center solution that runs on top of Nexus 9000 and APIC-enabled devices and enables abstraction and programmability of total network functionality via the Application Policy Infrastructure Controller (APIC).

Question 36

What is pyATS

Answer 36

a Python-based network device test and validation solution, originally developed by Cisco for internal use, then made available to the public and partially open-sourced.