Linux Sys Admin Interview Questions

1. What is the config file for configuring ipbonding.?
   /etc/modprobe.conf
2. How to check the runlevel of the server.?
   who -r  [or] runlevel
3. How to check the OS name.?
   "lsb_release  -a" in RHEL 4 , cat /etc/redhat-release
4. What is anaconda.? Why it is used.?
   Anaconda is the installation program used by Fedora, Red Hat Enterprise Linux and other distributions
5. What is the default size of MBR.?
   Ans:MBR is first sector of Hard Disk. Size is 512 bytes of which 446 bytes-Bootstrap,64 bytes - Partition table,2 bytes - signature (supports upto RHEL5) and 4KB (supports in RHEL 6)
6. What is the default size of inode.?
   Ans: Default inode size in ext3 filesystem is 128 bytes and in ext4 filesystem is 256 bytes.
7. What is parameter in dhcpd.conf related to PXE boot.?
8. How the tar command can be used to archive a particular set of files/folders.?
9. How the tar command can be used to exclude a particular set of files/folders while archiving.?
10. How to input a file/folder name to the tar command to include/exclude while archiving.?
11. Do you have exposure hosting environment.?
12. How do you perform kernel update (manually).?
13. How python is used to encrypt./decrypt?
14. What is the argument to set delimiter in awk.?
15. How do you tune Apache tomcat.?
16. How to input file in Squid, with a list of 100 websites to block.?
17. What is partition code for swap file system.?
18. How will you add a hard disk to mirror hard disk, when one of the hard disk in RAID fails.?
19. Have you worked in DNS/Domain/Mail setup.?
20. How to tune Apache.?
21. What is the use of lsattr/chattr.?
22. What is the use of setfacl/getfacl.?
23. How do you configure quota to /home file system.?
24. What is iptables.?
25. What are the monitoring tools in Linux.?
26. What is the use of sed.?
27. Have you got exposure in perl.?
28. Have you got experience in PHP/LAMP.?
29. How do you backup MySQL database.?
30. What are the ticket management tools.?
31. How do you check full duplex/half duplex settings feature available in command line?
32. Tell about mail client.?
33. What about ip bonding.? What are the different methods involved.?
34. What is the find command to delete files older than 22 days.?
35. What is MTA/MUA.?
36. What is yum.?
37. What is the default location of database used by yum.?
38. How doo you calculate umask value for files/directories.?
39. How will you generate and use key for login without password.?
40. How do you limit no of terminals opened by user in server.?
41. What is tcp wrappers.?
42. What is the difference between ext2/ext3?
43. How will you zip files/folders.?
44. How do you resize logical volme.?
45. What is last .? Which file is responsible for this output.?
46. How do you list the inodes used by file system.?
47. What is Selinux.? What are the 3 modes.?
48. Explain the entries in fstab file?
49. What is w.? Which file is responsible for it.?
50. What is sudo.? How many aliases are there.?
51. How will you edit sudo utility.?
52. How will you harden linux OS.?
53. How you got exposure to SOLARIS.?
54. Have you worked in RAID controller.?
55. How you worked in storage.?
56. How you worked in iDRAC console.?
57. What is the use of /etc/nologin?
58. What is rootnosquash in nfs.?
59. Where the database of DNS gets stored.?
60. What is POSTFIX.?
61. What is snapshot type backup.?
62. What is Samba.?
63. In tcp_wrappers ALL:ALL what is the result.?
64. How do you mount an .iso file in Linux.?
65. How do you a package in yum.?
66. What is the result of pxeboot -l .?
67. What is the file name to configure hard/soft no.of logins.?
68. What are the automations you have done using shell script.?
69. For loop to print temporary value.?
70. Have you used rhn satellite server.?
71. What is the difference between RHEL/CentOS.?
72. What is the command to create custom kickstart file.?
73. How do you change the context of a file.?
74. What is the command to test the configuration of sambe file.?
75. How to debug shell script.?
76. How to encrypt a parttition.?
77. How to delete a user along with his home directory in one command.?
78. How to change the runlevel of linux and switch to it without rebooting the box.?
79. What is inode.?
80. How to assign multiple ip address to a single interface.?
81. Difference between layer2 and layer3 network devices.?
82. How routing happens between two VLAN's in a single manageable switch.?
83. Difference between soft and hard link.?
84. Difference between soft and hard mount.?
85. Difference between level 2 and level 3 runlevel.?
86. Can we restart a particular process using kill command.?
87. What are the different file systems available.?
88. How do you create a swap file.?
89. What is superblock.?
90. Script to tranfer a file over FTP.?
91. What is multipath.?
92. How do you make sure whether LUN is mapped with server properly.?
93. How do you find the WWN number (or) Fiber channel ID in linux.?
94. Difference between resize2fs and ext2online.?
95. What are the pre-requisities of installing oracle 11g.?
96. What is the difference between LVM and LVM snapshot.?
97. Fields defined in /etc/passwd.?
98. What file contains list of currently mounted file systems.?
99. Command to display and modify your keyboard mappings in X windows.?
100. What is role of -F in the command in `shutdown -r -F now.`?
101. What is the tcpdump command to monitor the ip 172.168.1.1's port 443
102. What is the use of ethereal.?
103. What is the use of JBoss?
104. How do you troubleshoot issue in Jboss.?
105. Have you done kernel patching (or) update in linux.?
106. What is the port number to be opened for registering the linux server in rhn satellite.?
107. What is MX record.? How do you define it.? If two mail servers have same priority, to which mail server the client contacts initially.?
108. How do you raise a complaint with Red Hat customer support.?
109. What is ASM.?
110. When we use the command `cp file1 file2`, will there be any change in inode value of file2.?
111. What is the log file name for sendmail.?
112. What are the log file name for Apache.?
113. What is cronjob.? List the fields in it.?
114. How do you lockout a user account in linux.?
115. How do you debug a the LDAP client, not authenticating issue.?
116. How do you debug a webpage not opening issue, after multiple successful attempts before.?
117. What is the log file to check the quota full error.?
118. What is the command to check the ports opened in linux.?
119. How do you add a route in Linux.?
120. What is the difference between copy and rsync.?
121. What is the difference between port 21 and 20.?
122. What is clustering.?
123. How to failover RHEL cluster services.? Hint: Using clusvcadm.
124. How to change the binding interface online from Ethernet interface to other without any service impact.?
125. How to check the WWN number from linux.?
126. How to downgrade the filesystem from ext4 to ext3.?
127. How to check the Ethernet bonding status.?
128. How do you install a linux operating system in multiple physical bare metal servers.?
129. How do you revert to a working kernel after the Linux OS boot failure post patching due to new kernel issues.?
130. What are the different Ethernet bonding methods.?
131. What is the order of stopping a RedHat cluster services.?