Linux interview questions

 1).what is the differnece between dnf and yum pacakges 

into linux os ?


whatever activity we can do in yum packages , we can do the same activity into dnf packages its.


dnf packages :


 its provides the beter speed , performance and less memory consumptions .


this is the updated version of yum packages.



now am going to execute the command like as the ,


time dnf install package name -y


time yum install package name -y


after updating this packages into system , we have to see

the time differences.


2).How to block the root user account into the server for ssh?


3).what is the  difference between iostat and dstat in linux os ?


4)linux Monir ting cli commands 


5).Differences between linux 7 and linux 8 ?


6)difference between init vs systemd in linux os ?


init :


init is used to boot the process


7).what could be the reasons of a non bootable linux 

system or server?


boot loader issue :


corrupted grub 

incorrect boot loader settings

file system corruption

kernel issues

kernel panic


hardware problems:


it could be failed hard drive 

and may be memory issues it will be there


boot process configurations:


incorrect bios 

boot order.


they are different software are available into server.


driver or module conflicts


incompatible or misconfigured drivers


loadable kernel modules



software or configurations chnages:


software updates or chnages

incorrect fstab entries


secuirty :


some malware infections leads to non bootable linux os


insuficient disk space "


it may also lead system non bootable conditions


partioing errors:


incorrect partitioning


u need to boot into the os with single user mode


next we need to mount the os 


next we have to check the what is the issue is there?


8).How to troubleshoot linux kerenl panic issues into linux os ?


9).what is port number of ssh ?


10).what is main configuration file of ssh?

11).how to change the port number of ssh?


12).How to block ssh access for a single user?


13).what are the types of files in linux os?


14).what is the difference between file and directory ?


15).How to check open ports on a server?

16).how to check open ports on a remote server without login?


17).what is difference between public and private ip address?


18).what is the difference between hardlinks and softlinks?


19).How to check number of hardlink created for a file?


20).How to find the location of hardlink created for a file?


21).what is the port number of dhcp in linux os?


22).what is difference between tcp and udp ?


23).can you explain files of /etc/passwd 


24).how to enforce a user to reset passwords at next login?



25)how to change the shell of a user?


26).how to change the home directory of existing user?

27).How to change default home directory of users goin to be create in future ?


28).what are the common issues you have faced while doing ssh into a server?




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