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Monday, September 14, 2015

Linux Interview Questions and Answers for Freshers - Linvirtshell

1. What is Network Bonding ?

    Network bonding is the aggregation of multiple Lan cards into a single bonded interface to provide fault toleranceand high performance.
    Network bonding is also known as NIC Teaming

2. Mention all the network configuration files you would check to configure your ethernet card

    /etc/sysconfig/network-scripts/ifcfg-eth*
    /etc/sysconfig/network
    /etc/resolv.conf
    /etc/nsswitch.conf

3. How to change the ethernet card setting

    ethtool -s ethX speed 1000 duplex full

4. What does the last two sections define in fstab file?

    The 5th column tells the dump information if whether the partition has to be backed up. It it is "0" the filesystem will be ignored.
    The 6th column tells the order in which fsck command would check the filesystem on boot. If it is "0" then fsck won't check the filesystem

5. How to add & change the Kernel parameters ?

    To Set the kernel parameters in linux , first edit the file ‘/etc/sysctl.conf’ after making the changes save the file and run the command ‘sysctl -p’ , this command will make the changes permanently without rebooting the machine.

6. What is the difference between TCP and UDP protocol?

    TCP is a connection oriented protocol and contain the information of sender as well as receiver.

Eg: HTTP.FTP, Telnet

TCP is slower than UDP due to its error checking mechanism

    UDP protocols are connection less packets have no information to where they are going. These type of ports are generally used for broadcasting.For eg: DNS, DHCPUDP are faster

7. What are the possible ways to check if your system is listening to port 67

# fuser -v -n tcp 67
# cat < /dev/tcp/localhost/67
# ssh -vv localhost:67
# lsof -i :67
# nmap localhost | grep 67
# netstat -ntlp | grep 67
# telnet localhost 67

8. What is umask?

    In computing, umask is a command that determines the settings of a mask that controls which file permissions are set for files and directories when they are created. It also refers to a function that sets the mask, and to the mask itself,
    which is formally known as the file mode creation mask.

9. What is the default umask value for useradd command and where is it defined?

    Default umask value for useradd: 077
    /etc/login.defs

10. Will you be able to cd into a directory with only read permission?

    No, we need execute permission along with read to cd into directory

11. What is -R argument used for along with chmod command?

    To recursively apply the permission to all the directories including sub directories and files

12. How can you restrict a normal as well as root user from making any changes as well as deleting any file?

    chattr command

13. How do you give acl in Linux?

    Give individual permission using setfacl

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