1. When you login you get "$" prompt, what is the prompt for root?

   • ans: #

2. Explain the difference between grep and egrep?

   • Search online

3. What is the port # for DNS, NTP and NFS?

   • 53,123 and 111/2049

4. What is the configuration file name of DNS and where is it located?

   • /etc/named.conf

5. How many new directories will be created after running the following command

mkdir {a..c}{1..3}
# ans: 9

1. Your PC is configured with a DNS server address but not the default gateway. Can the PC access internet?

   • No

2. What is the difference between IP and Gateway?

   • Search online

3. Can you assign one static IP to 2 computers, if not then why?

   • No because it will create IP conflict

4. How to change IPs address to static?

   • ifconfig x.x.x.x

5. You are trying to ping a server by hostname and you get an error message, "ping: unknown host …". What could be the reason and how to solve the problem so you can ping it by hostname?

   • Check for /etc/hosts or DNS to see if it has hostname to IP entry

6. Explain the difference between relative and absolute path?

   • Absolute path starts from / where relative path is your current directory

7. List 3 different methods of adding user?

   • Search online

8. What is the command to change file/directory ownership and group?

   • chown and chgrp

9. List any 3 type of filesystem?

   • ext4,NTFS and FAT

10. When you login you get a message on the screen. What is the name of that file and where is it located?

    • /etc/motd

11. What is /bin directory used for?

    • Search online

12. What are the different types of DNS Server

    • Master and secondary

13. How to change a user password?

    • passwd username

14. What is the version of Redhat Linux you have experience with?

    • 7.4

15. List any 4 linux distributions?

    • Redhat, CentOS, Ubuntu and SUSE

16. How to logoff from the system?

    • exit

17. Give any 3 examples of operating systems?

    • Windows, Linux and MAC

18. How to create a directory?

    • mkdir

19. Where are the zone files located for DNS service?

    • /var/named/zonefiles

20. How to check kernel version?

    • uname -a

21. Which directory has all the configuration files?

    • /etc

22. How to become root user from a regular user?

    • su –

23. How many mega bytes in 1 giga bytes?

    • Search online

24. What is the purpose of having different network ports?

    • So the communication of each application goes through a dedicated port

25. How to display first column of a file?

    • cat filename | awk ‘{print $1}’

26. What is the name of DNS rpm package?

    • bind

27. What is the difference between nslookup and dig commands?

    • Search online

28. How to check your user id and group id?

    • id

29. How to check a file’s permission?

    • ls –l

30. What is the difference between “kill” and “kill -9” command?

    • Search online

31. What is subnet?

    • Search online

32. You are troubleshooting an issue with Redhat support and they have asked you to send the contents of /etc directory. How and which method you will use to transfer the contents?

    • tar (compress) the entire /etc directory and ftp

33. What is root home directory?

    • /root

34. What is rsyslogd deamon and its purpose?

    • Search online

35. Your company has terminated a server administrator. What is first thing as an administrator you should do to enhance the security?

    • Change root password

36. How to check the computer name or host name in Linux?

    • hostname

37. Which permission allows a user to run an executable with the permissions of the owner of that file?

    • First 3 bits should have x

38. What is the command to untar a tarred file?

    • untar

39. What is /proc directory used for?

    • Search online

40. What is the purpose of nsswitch.conf file

    • It tells the system where to go to resolve hostnames

41. List 3 basic commands to navigate the filesystem?

    • cd, pwd and ls

42. Which service/daemon should be running on the server that allows you to connect remotely?

    • sshd

43. What is the purpose of firewall?

    • Search online

44. List any 3 IT components?

    • Hardware, OS and Applications

45. Which directory has all the commands we use, e.g. ls, cd etc.?

    • /usr/bin or /bin

46. What is the difference between memory, virtual memory and cache?

    • Search online

47. Which of the following is correct?

    • [x] a. Hardware  Operating System  Users

    • [ ] b. Operating System  Users  Hardware

    • [ ] c. Database  Hardware  Users

48. Which of the following is a communication command?

    • o grep

    • o mail

    • o touch

    • o cd

49. How to rename a file or directory?

    • mv

50. How to change a hostname in Linux?

    • Search online

51. How to check network interfaces in Linux?

    • ifconfig

52. Why is “tail –f logfilename” command used most often and what does it do?

    • It will output all incoming logs in real time

53. What type of hardware have you worked on?

    • You should get yourself familiar with Dell, HP and UCS hardware by going online and check the vendor websites

54. How to sort a file in reverse order?

    • cat filename | sort –r

55. What is the name of operating system that runs Unix?

    • Solaris, HP-UX etc.

56. List all byte sizes from smallest to largest?

    • Search online

57. How to check the total number of partition in Linux?

    • fdisk -l

58. How to access a linux system from a linux system?

    • ssh

59. Explain the procedure of bonding 2 NICs or interfaces together?

    • Search online

60. What is the exact command syntax to list the 5th column of a file and cut the first 3 letters?

    • cat filename | awk ‘{print $5}’ | cut –c1-3

61. What is /etc/hosts file used for?

    • To resolve hostnames with IP address

62. List any 3 options of ‘df’ command and what they are used for?

    • Search online

63. What is the command to change file/directory permissions?

    • chmod

64. What is the purpose of pipe (|)?

    • To combine multiple commands

65. What is /etc directory used for?

    • For configuration files

66. Which command is used to list files in a directory?

    • ls -l

67. There is a command which gives you information about other commands, please explain that command and what is it used for?

    • man

68. How to delete a file and a directory?

    • rm filename and rmdir dirname

69. What is the difference between “tail” and “tail -10”?

    • None

70. List 4 commands to display or read a file contents?

    • cat, more, less, vi

71. Which command is used to read the top 5 lines of a file?

    • head -5 filename

72. What are the different commands or methods to write to a file?

    • echo > filename and vi filename

73. What is swap space and how to check swap space?

    • Search online

74. What is inode and how to find an inode of a file?

    • Search online

75. Which file to edit for kernel tuning?

    • Search online

76. What is the latest version of Redhat?

    • Search online

77. Name the command to find specific word from a file?

    • grep word filename

78. You have scheduled a job using crontab but it does not run at the time you specified, what could be the reason and how would you troubleshoot?

    • Check your system time

    • Check your crontab entry

    • Check /var/log/messages

79. How to check system hardware information?

    • dmidecode

80. How to check network interface MAC address?

    • ifconfig

81. If I don’t want others to read my file1, how to do that?

    • Remove r from the last 3 bits of file permission

82. What is the purpose of “uniq” and “sed” command?

    • Search online

83. Which command is used to list the contents of a directory in the most recent time and in reverse order, meaning the most updated file should be listed on the bottom?

    • ls –ltr

84. What is the difference between tar, gzip and gunzip?

    • Search online

85. What are the different ways to install and OS?

    • DVD, DVD iso and network boot

86. How to view difference between two files?

    • diff file1 and file2

87. You noticed that one of the Linux servers has no disk space left, how would you troubleshoot that issue?

    • If running LVM then add more disk and extend LVM If not running LVM then add more disk, create a new partition and link the new partition to an existing filesystem

88. How to check Redhat version release?

    • uname –a or /etc/redhat-release

89. What is the difference between TCP and UDP?

    • Search online

90. What is a zombie process?

    • Search online

91. How do you search for a pattern/word in a file and then replace it in an entire file?

    • sed command

92. Explain the purpose of “touch” command?

    • To create an empty file

93. If a command hangs, how to stop it and get the prompt back?

    • Ctrl C

94. Which command is used to count words or lines?

    • wc

95. How to check the number of users logged in?

    • who

96. What is the command to view the calendar of 2011?

    • cal 2011

97. Which command is used to view disk space?

    • df –h

98. How to create a new group in Linux?

    • groupadd

99. What is the command to send a message to everyone who is logged into the system?

    • wall

100. Which command is used to check total number of disks?

     • fdisk –l

101. What is an mail server record in DNS?

     • MX

102. What does the following command line do?

     ps -ef | awk '{print $1}' | sort | uniq
     

ANS: List the first column of all running processes, sort them andremove duplicates

1. You get a call that when a user goes to www.yourwebsite.com it fails and gets an error, how do you troubleshoot?

   • Check for user internet

   • Check to see if user computer has DNS for hostname lookup

   • Check to see if the server is up that is running that website

   • Check to see if the server’s web service is running

   • Check for DNS availability which is resolving that website

2. List 4 different directories in /?

   • /etc, /bin, /tmp, /home

3. What is the output of the following command:

   • $tail -10 filename | head -1

ANS: It will show the first line from the last 10 lines of a file

1. What are the different fields in /etc/passwd file?

   • Search online

2. Which command is used to list the processes?

   • ps –ef

3. What is the difference between “hostname” and “uname” commands?

   • Hostname will give you system name and uname will give you OS information

4. How to check system load?

   • top and uptime command

5. How to schedule jobs?

   • crontab and at

6. What is the 3rd field when setting up crontab?

   • Day of the month

7. What is the command to create a new user?

   • useradd

8. What is the “init #” for system reboot?

   • 6

9. How to restart a service?

   • systemctl restart servicename

10. How to shutdown a system?

    • shutdown or init 0

11. What is “ftp” command used for?

    • To transfer files from one computer to another

12. Explain cron job syntax? First is minute, second is..?

    • Min, house, day of the month, month, day of the week and command

13. How to delete a package in Linux?

    • rpm –e packagename

14. What is the file name where user password information is saved?

    • /etc/shadow

15. Which command you would use to find the location of chmod command?

    • which chmod

16. Which command is used to check if the other computer is online?

    • ping othercomputer

17. Please explain about LAN, MAN and WAN?

    • Search online

18. How to list hidden files in a directory?

    • ls –la

19. What is the difference between telnet and ssh?

    • ssh is secure where telnet is not

20. How to run a calculator on Linux and exit out of it?

    • bc and quit

21. List any 4 commands to monitor system?

    • top, df –h, iostat, dmesg

22. You are notified that your server is down, list the steps you will take to troubleshoot?

    • Check the system physically

    • Login through system console

    • Ping the system

    • Reboot or boot if possible

23. What is difference between static and DHCP IP?

    • Search online

24. How to write in vi editor mode?

    • i = insert, a = insert in next space, o = insert in new line

25. What is the difference between “crontab” and “at” jobs?

    • crontab is for repetitive jobs where at is for one time job

26. What is vCenter server in VMWare?

    • Search online

27. What is “dmidecode” command used for?

    • To get system information

28. What is the difference between SAN and NAS?

    • Search online

29. What is the location of system logs? E.g. messages

    • /var/log directory

30. How to setup an alias and what is it used for?

    • alias aliasname=”command”

    • It is used to created short-cuts for long commands

31. What is the purpose of “netstat” command?

    • Search online

32. What are terminal control keys, list any 3?

    • Crtl C, D and Z

33. Which command(s) you would run if you need to find out how many processes are running on your system?

    • ps –ef | wc –l

34. What are the different types of shells?

    • sh, bash, ksh, csh etc.

35. How to delete a line when in vi editor mode?

    • dd

36. Which is the core of the operating system?

    • [ ] a) Shell

    • [x] b) Kernel

    • [ ] c) Commands

    • [ ] d) Script

37. Which among the following interacts directly with system hardware?

    • [ ] a) Shell

    • [ ] b) Commands

    • [x] c) Kernel

    • [ ] d) Applications

38. How to save and quit from vi editor?

    • Shift ZZ or :wq!

39. What is the difference between a process and daemon?

    • Search online

40. What is the process or daemon name for NTP?

    • ntpd

41. What are a few commands you would run if your system is running slow?

    • top, iostat, df –h, netstat etc.

42. How to install a package in Redhat Linux?

    • yum install packagename

43. What is the difference between “ifconfig” and “ipconfig” commands?

    • ifconfig for Linux and ipconfig for Windows

44. What is the first line written in a shell script?

    • Define shell e.g. #!/bin/bash

45. Where is the network (Ethernet) file located, please provide exact directory location and file name?

    • /etc/sysconfig/network-scripts/ifcfg-nic

46. Why do we use “last” command?

    • To see who has logged in the system whether active or logged off

47. What is RHEL Linux stands for?

    • Search online

48. To view your command history, which command is used and how to run a specific command?

    • history and history #

49. What is NTP and briefly explain how does it work and where is the config files and related commands of NTP?

    • Search online

50. How to disable firewall in Linux?

    • Search online

51. How to configure mail server relay for sendmail service?

    • Edit /etc/mail/sendmail.mc file and add SMART_HOST entry

52. Where is samba log file located?

    • /var/log/samba

53. What is mkfs command used for?

    • To create a new filesystem

54. If you create a new group, which file does it get created in?

    • /etc/group

55. Which file has DNS server information (e.g. DNS resolution)?

    • /etc/resolv.conf

56. What are the commands you would run if you need to find out the version and build date of a package (e.g. http)?

    • rpm –qi http

57. On the file permissions? What are the first 3 bits for and who is it for?

    • Read, write and execute. They are used for the owner of the file

58. How to create a soft link?

    • ln –s

59. How to write a script to delete messages in a log file older than 30 days automatically?

    • Search online

60. How to quit out of “man” command?

    • q

61. Which command is used to partition disk in Linux?

    • fdisk

62. What is the difference between “shutdown” and “halt” command?

    • Search online

63. What is the exact syntax of mounting NFS share on a client and also how to un-mount?

    • Search online

64. What experience do you have with scripting, explain?

    • if-the, do-while, case, for loop scripts

65. How to get information on all the packages installed on the system?

    • rpm –qa

66. Explain VMWare?

    • Search online

67. You are tasked to examine a log file in order to find out why a particular application keep crashing. Log file is very lengthy, which command can you use to simplify the log search using a search string?

    • grep for error, warning, failure etc. in /var/log/messages file

68. What is /etc/fstab file and explain each column of this file?

    • Search online

69. What the latest version of Windows server?

    • Search online

70. What is the exact command to list only the first 2 lines of history output?

    • history | head -2

71. How to upgrade Linux from 7.3 to 7.4?

    • yum install update

72. How to tell which shell you are in or running?

    • $0

73. You have tried to “cd” into a directory but you have been denied. You are not the owner of that directory, what permissions do you need and where?

    • - - - - - - - r – x

74. What is CNAME record in DNS?

    • Entry for hostname to hostname

75. What is the name of VMWare operating system?

    • ESXi

76. What is the client name used to connect to ESXi or vCenter server?

    • vSphere client

77. You get a call from a user saying that I cannot write to a file because it says, permission denied. The file is owned by that user, how do you troubleshoot?

    • Give write permission on the first 3 bits

78. What is the latest version of VMWare?

    • Search online

79. What is the name of firewall daemon in Linux?

    • firewalld

80. Which command syntax you can use to list only the 20th line of a file?

    • Search online

81. What is the difference between run level 3 and 5?

    • 3 = Boot system with networking, 5 = boot system with networking and GUI

82. List a few commands that are used in troubleshooting network related issue?

    • netstat, tcpdump etc.

83. What is the difference between domain and nameserver?

    • Search online

84. You open up a file and it has 3000 lines and it scrolled up really fast, which command you will use to view it one page at a time?

    • more or less

85. How to start a new shell. E.g. start a new ksh shell?

    • Simply type ksh, or bash

86. How to kill a process?

    • kill processID

87. How to check scheduled jobs?

    • crontab –l

88. How to check system memory and CPU usage?

    • free and top

89. Which utility could you use to repair the corrupted file system?

    • fsck

90. What is the command to make a service start at boot?

    • systemctl enable servicename

91. How to combine 2 files into 1? E.g. you 3 lines in file “A” and 5 lines in file “B”, which command syntax to use that will combine into one file of 3+5 = 8 lines

    • cat fileA >> fileB

92. What is echo command used for?

    • To output to a screen

93. What does the following command do? echo This year the summer will be great > file1

    • It will create a new file “file1” with the content as “This year the summer will be great”

94. Which file to modify to allow users to run root commands

    • /etc/sudoers

95. You need to modify httpd.conf file but you cannot find it, Which command line tool you can use to find file?

    • find / -name “httpd.conf”

96. Your system crashed and being restarted, but a message appears, indicating that the operating system cannot be found. What is the most likely cause of the problem?

    • The /boot file is most likely corrupted