LINUX INTERVIEW QUESTIONS

Hello Friends,

We all might have faced various interview questions and well aware of as a beginner how tough to clear it at first attempt almost all have too many questions.

Below are some interview question that have faced during my journey in Linux/Unix journey !!

"TELL ME SOMETHING ABOUT YOUR SELF"

0. As usual !!! "Tell me something about yourself"? An annoying question? but everyone have to face this and have to be well prepared as first impression might be your last impression .

Don't loose your confidence or get afraid as you have to sell your knowledge in this competitive market and if you failed here doesn't mean path has end ..

Let's find out how to answer this in well organized order in < 2-3 minutes .

1. Your NAME in full
2. Your qualification in short start with 1-10th -> 11-12th -> Degree 

3. Fresher -> Your college project brief explained
    Lateral -> Your first job how you got and roles & responsibility

                -    Small intro about your previous all experience
                -   Current Job detailed info like day2day activities, roles

                -   Future opportunity at your current job
                -   Your future goal (Only if have left some time)

4. That's it from my end IF anything else you want to know then please ask !!

Note: - Don't explain much about your family background unless being asked :)
         - Don't be more overconfidence

         - Don't show your ego mean judge interviewer and try your best that Interviewer will not feel like he is more technically stronger than me :)
         - Don't be short tempered
         - Include technical skill-sets for which you have confidence 

         - Don't be too over smart, as that might create negative impression towards like "WILL SEE HIM IN TECHNICAL ROUND!!!  '(';')'   '(';')' ...

         - Keep cool & calm, as this is not your last opportunity many more has to come at your path .

Okay lest start with some Linux interview technical questions :

Basic Level 1 for freshers or < 2 yr exp..

Expert Level for lateral 

1. What is Linux 
2. Diff Linux & Unix 
3. Diff RHEL 5/6 
4. What's new in RHEL 7
5. Linux boot process in brief 
6. Port numbers on FTP 
7. Port number of telnet, smtp, dns, dhcp, ntp, http, https
8. How to check/edit other users cron entries
9. What is user shell
10. How to check available shells
11. How to change your current shell 

DNS:

1. What is DNS 
2. How DNS works 
3. Types of DNS
4. Types of records in DNS 
5. How to check DNS lookup 
6. How to update DNS zone without service restart
7. How to check any error in zone file
8. What & Why NS record in DNS
9. Master and slave how it's working 
10. How to ensure updates send to slaves
11. Static vs Dynamic DNS zones
12. How to update dynamic zones & usages 
13. Fields in zone file 
14. reload for specifiz domain zone 

CRONTAB:

1. What is crontab
2. Fields in crontab
3. Where is user specific cron file
4. What is system specific cron, where are they defined  
5. Use of /etc/crontab file 
6. Eg. Schedule a script run every day at 11:00pm
         Schedule a script run every 2 minutes

Backup:

1. Any backup tools you know?
2. What is diff tar and zip 
3. gzip pack and unpack 
4. cat gzip file 
5. bazip2 pack and unpack 
6. cat bazip2 file 
7. extract without effecting current file 
8. extract to specific dir 

Yum & rpm:

   yum: 

1. yum package name 
2. Find current available repos
3. Install from specific repo
4. Install local rpm
5. Find all available version of package
6. Find when package was installed 
7. Install a specific version of package 
8. Check package integrity 
9. Clear yum cache, required in which case example .
10. Find package all files 
11. How to setup YUM server 
12. How to setup yum client
13. How to setup yum proxy

    rpm:

1. rpm package name 
2. install/update/remove etc 
3. Find when package last updated
4. Find package info, files, dependencies 
5. What is rpmdb
6. how to re-build

Mail Server:

Do you have experience on any mail server ?

Postfix: 

1. How Postfix or any mail server works 
2. What is configuration file
3. PORT Number 
4. Check service running or not and listening on which IP
5. How to send a test mail 
6. Log file path
7. Check mailq 
8. Flush mailq
9. Resend, force retry all mails in queue 
10. How to handle maillog rotation 
11. Listen on localhost why ?
12. Listen is specific IP why ?
13. Diff master and client setup basic 
14. What is master.cf 
15. Filter any specific user mail -> DISCARD
16. Mail to specific user -> DISCARD 
17. Allow mail sent to specific domain only 
18. Allow only specific set of users to send mail 
19. Allow mail form a specific subnet
20. Minimum requirement to setup postfix mail server
21. Sent mail lost troubleshooting steps .

Specification:

1. Find Physical or Virtual
2. Find System vendor name i,e Manufacturer name 
3. Find total RAM  
4. Find total swap
5. Find total socket, Core, CPU's on server
6. Find System serial number 
7. Find HBA cards

Troubleshooting:

1. Total current Load on server, how to check 
2. What is load average, how and where to find and statics interval
3. Total cpu utilization on server how to calculate
4. Total memory utilization
5. Total swap utilization 
6. Add additional swap? how ?
7. Which process consuming more CPU
8. Which process consuming more RAM
9. Which process consuming more SWAP
10. Which process consuming more no of process 
11. How to find total number of process thread initiated by a process 
12. What is i/o on system, how to find 
13. Which process causing high i/o
14. Diff paging and caching 
15. What is cpu steal time 
16. What is memory over-commit
17. Find troubleshoot memory leak
18. How to enter in single user mode 
19. diff single user and emergency mode 
20. How to recover boot grub password 
21. How to clear cache, why its required and what would be impact of this 

Boot level :

1. How to set grub password
2. How to set default kernel to boot 
3. How to change kernel parameters during boot 
4. How to repair FS 
5. What is GRUB 
6. Size of MBR, fields in MBR, PT size in MBR
7. What is rescue mode 
8. How to enter in rescue mode and why required example 
9. Take MBR backup and repair 

Networking:

1. How to assign IP address
2. How to assign  virtual IP address
3. How to assign temporary IP address
4. How to change hostname permanent
5. How to assign temporary hostname 
6. What is Gateway
7. How to assign Gateway 
8. What is domainname 
9. TCP vs UDP with example of each 
10. OSI layer 
11. How many virtual IP you can assign to a single interface .
12. What is route table 
13. How to update route table temporary 
14. How to update route table permanent
15. What is bonding
16. How to setup network bonding for 2 interface 
17. Mode of bonding 
18. Steps of bonding 
19. Check current status of bond interface 
20. Check members of bond
21. Bonding vs Bridging in Linux
22. What is ARP
23. What is network boot
24. What is iptables
25. Tables in iptables
26. Write iptable to block use of sshd service via port 22 from outside of range 192.168.8.10-192.168.8.50
27. What is tcpdump 
28. tcpdump take dump of all packets coming from host1 and host 2 on port 3030 on ethernet eth2 and write to file /tmp/a.pcap
29. Read tcpdump file 
30. What is ip_forwarding 

Setup:

1. How to install Linux RHEL/CentOS OS 
2. Types of installation 
3. What is PXE boot 
4. What is network boot 
5. Rapid Kickstart installation 
6. Any other installation method you know 

Volume Management ( LVM ) :

1. What is LVM 
2. What is File system 
3. Advantage of ext4 over ext3
4. Advantage of xfs over ext4
5. What are the fields in /etc/fstab
6. Ex: create a LV of 5GB and mount of /test
   Disk1: /dev/sda
   Disk1: /dev/sdb
   VG to create: VG01 with above 2 disk
   LV: mytestlv
   Mount with both dump & pass enabled ? What are these fields ?
7. How to extend LV
8. how to reduce LV
9. How to extend VG
10. how to reduce VG 
11. How to take snap of LV
12. How to destroy LV, VG, PV 
13. Find number of PV's in VG
14. Find free available size in VG
15. Create LV with all availabel free size in VG
16. Change VG parameters .  

Scripting:

1. Do you have experience on any scripting language
2. Bash shell scripting ?
3. What is first line of script eg. "#! /bin/bash" and why it's there
4. How to pass arguments in script 
5. How to read arguments in script 
6. How to define array 
7. How to define float value
8. How to define string
9. How to print no of arguments passed in script 
10. What is echo $#
11. What is echo $@
12. Print 1 to 10 in reverse order
13. Synatx of for loop
14. Syntax of while loop
15. Syntax of if else
16. Syntax of neted if else
17. Syntax of case statement
18. What is getopts
19. What AWK stands
20. AWK to print 3rd column
21. Using grep find how many times word "HELLO" appear in file1
22. Using egrep find if file1 contains HELLO1 and HELLO2
23. Diff grep and egrep 
24. Use sed to replace "hello" to "sello" in file

Others:

1. USe of ip_farwording
2. Where is config file of sshd service.
3. What is tunnel
4. What is mutt
5. Fields in top command meanings
6.     1>load average 2> %id     3> Mem: 4> SWAP
7. What is the use of swap partition
8. Can we increase swap partition size how
9. Syntax of for loop in bash
10. Can we change vsftpd default directory location
11. Can we change Default Directory in apache
12. Can we use index.php insted of index.html as default page in apache how .
13. visudo command will open file?
14. Diff RHEL & Centos
15. Diff LILO GRUB
16. Advantages of GRUB
17. What is iptables, Firewall, netfilter ..?
18. What is cluster & virtualizaton just basic, what you understand by term.
19. What does 2nd column represent in #ls -l output 

 .... N.. MANY MORE COMING SOON .... KEEP LEARNING...!!!!

# Faced any problem Feedback in above contact me

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