I have compiled few Interview Questions for Linux Admins. I will keep adding this in future.
Questions:
Where are user accessible binaries are stored?
How do you check mounted filesystem usage
How do you check size of folder
How to get free inodes in filesystem?
Command to check type of file weather it is binary or shellscript or image
Command used to check all the mounted partitions OR which command will show me the mounted filesystem is read only or read-write enabled
If i want a filesystem which should get mounted while system startup, then in which file I need to add entry
Which scripts execute at last when system gets startup
Which script initialize the System Daemons while booting up RedHat 6
If administrator wants to display a message after login on every users screen, then in which file Admin should enter the message?
Command to check if dhcp server is installed in RedHat Linux system or not?
How to delete Directory?
Tell me the command to create a Directory tree in one command
Where are the samba configuration files are generally stored in RedHAT based Linux system?
How to start Networking service in debian based Linux?
How to list hidden files inside /abc directory?
Tell me command to compare two ASCII files
Tell me the filename to edit for adding NFS share?
Which Linux modules get loaded after starting NFS?
Command to check partitions in Linux
How do you change mysql admin password ?
How to check Mysql processes?
How to get the path of command ?
Explain the output of uptime command
How to get List of kernel Modules loaded in Memory
What is the partition id of Swap Partition?
How to create LVM ? Where LVM stores Cache Files?
If you want New file should be created with rw–r—r– ?
What is proc?
What is the difference between Absolute & Relative Path ?
how to get only last columnt of ls -l output
How to add stickybit?
Linux Troubleshooting
Where MBR stored in Linux? Size of MBR?
If linux machine has some issue which log file you will check first ?
If there are any hardware related issues, then which command you will run first to check
If you exported NFS share but you are not able to access it on client then how will you troubleshoot?
How will you check the process eating up more CPU?
How to check if port 443 is open or close?
If I am not able to create a single file on mounted filesystem, what can be the reasons?
Where are the kernel tunable parameters?
What is the use of Vmstart?
In which logs you will see login failure messages?
What is iostat?
Suppose if you monted filesystem but that drive got physically disconnected due to some issues, now I am not able unmount it and mount it as well. Where you will check?
Linux Networking
How to add default route in Linux?
Which command is used to check IP addresses of Networking Cards attached to the system?
Which command is used to check Network Link is up or not?
On which port SSH serviec listens
If I have to configure Linux Box as a router, which kernel parameter I have configure
What is iptables ? What are the default tables in iptables?
What is the difference between stateless & statefull firewall?
what is tcp_syncookies?
How to enable tcp_windowscalling?
Difference between Active & Passive
On which port FTP Server listens
Why nslookup command is used?
How to get Authoritive NameServers of abc.com domain using dig?
Networking:
Tell me about TCP Handshaking
Use of SNMP ?
How do you monitor Networking Device using SNMP ?
Which command is used to test or communicateSNMP server?
What is VPN & Types of it?
What is OSPF?
What is STP?
How much maximum number of IP addresses you will get in 192.168.0.0/25 Network?
What is the tolarance value for RAID6
What are the basic types of Virtual Hosting in Apache?
On which port MySQL listen?
On Which port Samba Service Listen
How Nagios server communicate with Nagios client?
User Management:
When you add any user which files get modify in /etc
Tell me command to add user in Debian base Linux
Which library actully does the local authentication in Linux
Tricky Question:
Someone has made chmod UN-exectubale by running “chmod -x chmod”. How would you fix the problem?
