Devops QS

Question 1

What is DEVOPS

Answer 1

DEVEOPS IS A SOFTWARE DEVOLOPMENT METHODOLOGY THAT COMBINES PROCESS AND TECHNOLOGY AND PROVIDES REALBILTY TO SOFTWARE DELIVERY

Question 2

What is open source software?

Answer 2

open souce software is a software were the code is able to seen and is acessible to the publice where they can change and deliver it as they see fit

Question 3

What are the differences between Linux vs Windows?

Answer 3

linux is a free open source software that is 4 times more efficient has more stability
windows is not free its less efficient and uses graphical use interface

Question 4

Explain Linux file system hierarchy

Answer 4

its a reference to the linus directory structue where all the file and folders reside under the parent folder

Question 5

What are the differences between CentOS and RedHat?

Answer 5

centosos is more stable operating system it does not have support
redhat less stable but it requires payment to be supported

Question 6

What are the differences between CentOS 6 vs 7 vs 8?

Answer 6

centos 6 ,7, and 8 are the end of their life cycles. centos 6 used ext4 filesystem , centos 7 used ifs filesystem , centos 8 used
centos 9 is up to date
uses the xfs,btfs filesytem

Question 7

Explain Linux File Permissions

Answer 7

is set of permissions that determine who are given to access system to be able to read write and execute file

Question 8

What is CLI and GUI?

Answer 8

CLI is the command line interface which is used in linus operating system to have commands outputs
GUI is the graphical user interface which is used by windows

Question 9

How do you create a directory in Linux?

Answer 9

you create directory in linux by using the mkdir command

Question 10

how do you create an empty file in linus

Answer 10

create an empty file by using the touch command

Question 11

how do you check the current working directory

Answer 11

you check by using the pwd command

Question 12

if a user knows the command but does not know how to use it, how can she get help

Answer 12

you can get help by using the man command which stands for manual followed by the command it will give you a descriptive information on how to use it or you can use google

Question 13

what does / represent

Answer 13

it represent the parent folder where all the files and folders are under

Question 14

if a user need to read the content of the file on screen , and set the line numbers what command can he use

Answer 14

the read the content he or she can use the cat command with -n see the numbers with the information printed

Question 15

If a user needs to find out the number of lines and words in a file, what command can he/she use?

Answer 15

he/she can use the wc command

Question 16

On a file using “vi” command, how can a user search for a word?

Answer 16

you can use the slash followed by the word

Question 17

How to set numbers, using “vi” command mode?

Answer 17

in vi command you first press the escape button for the command then type the colon then by set number

Question 18

What command do you use to find a string in a file?

Answer 18

you can use the grep command

Question 19

What command do you use to find a file?

Answer 19

you can use the find command

Question 20

How to find a file in the system, owned by a specific user?

Answer 20

you use the find command follwed -user

Question 21

How to delete 100 lines in a file, from cli?

Answer 21

to delete 100
you will use d#d which deletes multiple lines

Question 22

What command would you use to copy specific columns from a file?

Answer 22

the command you would use the awk or the cut command

Question 23

What is a Linux shell? What are the popular shells in Linux?

Answer 23

linux shell is program where input command gives the operating system to peform
some populare shells zsh bash shell ksh korn

Question 24

What is the difference between ‘standard error’ and ‘standard output’?

Answer 24

‘standard output’ is the terminal screen where the response are shown from the command
standard error the default error output devicce which is used to write all system error messages

Question 25

How to rename a file/folder in Linux?

Answer 25

to rename a file you can use the mv command followed by source and then destination

Question 26

By default which folder has the home directory of the users added to the system?

Answer 26

/home folder of users in the system

Question 27

Which command will show the current kernel running in your system?

Answer 27

the uname command will show the current kernel of system

Question 28

There is a file under /etc folder that will show the current release of the operating system, what is the name of the file?

Answer 28

os-release”

Question 29

Explain /proc folder

Answer 29

the proc folder is the virtual file stystem for running os and applications provides information about the system’s state and kernel

Question 30

Explain /mnt folder

Answer 30

subdirectory of the root directory in Linux and other Unix-like operating systems that serves as a temporary mount point for file systems.
used to mount storage devices like USB drives, CDROMs, and floppy disks.

Question 31

Explain /etc folder

Answer 31

central location for system configuration files and directories

Question 32

Explain /root folder

Answer 32

the top-level directory in a computer’s file system. It’s the starting point for organizing all files and folders, and is often reserved for essential system files

Question 33

Explain /home folder

Answer 33

a personal storage space for a user’s files, configurations, and data

Question 34

Where do you find log files in a CentOS machine?

Answer 34

find in /var/log directory

Question 35

What are some of common log files you work with?

Answer 35

apache logs
applications logs
system logs

Question 36

What is an inode?

Answer 36

file data structure that stores information about any Linux file except its name and data.

Question 37

What types of file systems do you know?

Answer 37

ext4 red hat os 6
xfs red hat os7
btrfs rehat os9
ntfs windows fs
apfs apple fs

Question 38

What is a swap space? How do you check for swap usage

Answer 38

the secondary memory in storage can use the free command to check for usage

Question 39

What is load average in Linux?

Answer 39

a metric that measures the average system load over a certain period. I

Question 40

How do you check load average?

Answer 40

you can use the uptime command

Question 41

How much load average is too much for your system?

Answer 41

consistently higher than the number of CPU cores

Question 42

How do you find a processes using most CPU?

Answer 42

using the top command displays all running processes

Question 43

What command do you use to check for disk usage?

Answer 43

df command to check

Question 44

A client is complaining that she/he can’t ssh to a server, how would you troubleshoot this issue?

Answer 44

first i would replicate problem to make if the problem was real
then i would check the server is running

Question 45

A client is complaining that she/he can’t connect to a web server, how would you troubleshoot this issue?

Answer 45

• Replicate the problem (Ask for a screenshot) (Example: wrong domain)
  
  • Check Digital Ocean and see if VM is running
  • SSH to VM
  • Check for SELinux (Disable)
  • Check if Web Server is running (systemctl status httpd)
  • Firewall
    Clients > Cloud Firewall > Linux{ Linux Firewall > Web Server

Question 46

WordPress is complaining about database connectivity issue, how would you troubleshoot?

Answer 46

• Replicate the problem (Ask for a screenshot) ( mysql -u wpuser -p XXXXXX )
  
  • Check Digital Ocean and see if VM is running
  • SSH to VM
  • Check for SELinux (Disable)
  • Check if MySQL is running (systemctl status mysqld)
  • Wrong Username?
  • Wrong Password?