ibm aix interview questions and answers

AIX Faqs-->2

71. When there is a problen in a system what to do first ?

Ans: lookinto error log by errpt –a command

72. What is difference between errorlog and alog  files ?

Ans: alog gives the information on boot error.

73. What is the boot sequence in AIX and give the details of each step of booting?

Ans: 

74. What is mksysb backup? What are advantages we get out of it?

Ans: rootvg backup, sytem can be restored in case of failure, PP size can be changed, filesystem size can be reduced by shrink

75. Can we do the mksysb backup and savevg of other vg on same tape? Give the reason?

Ans: No

76. What is the procedure to retrieve only /etc/hosts file from mksysb tape? Give commands with exact syntax?

Ans: #tctl –f /dev/rmt0 rewind

  #restore –s4 –xqvf /dev/rmt0.1 ./etc/hosts

77. How you increase the size of a file system by 5GB? Give command details?

Ans: #chfs –a size=+5G /data

78. What are the tools available for performance monitoring?

Ans: sar, vmstat, topas

79. When you tell the system is CPU Bound or memory bound?

Ans: Run the sar command. If the value of %USER + %SYS is more than 80% we call the system is CPU bound. Run the vmstat command. If PI and PO is high we call the system to be memory bound.      

80. How will you check a given file system is large filesystem enabled?

Ans: lsfs –q fsname, if bf=true the given filesystem supports big filsystem

81. What is command to see MAC address of NIC?

Ans: # lscfg –l ent0 –v

82. How will you check the serial no of the system?

Ans: uname –a

83. How will you see the parent device for en0?

Ans: # odmget –q “name like en0” CuDv

84. What is the fastpath for SSA RAID?

Ans. # smit ssaraid

85. How will you check the given hdiskn has how many no of Pdisks of your SSA box?

Ans: # ssaexlate –l hdiskn

86. What is the command to list all supported hardware by your system?

Ans: lsdev –P –H

87. How will you list the total no adapters your system have?

Ans: lsdev –Cc adapter

88. What is the command to see your dumpdevice?

Ans: sysdumpdev –l

89. What is the default dumpdevice?

Ans: /dev/hd6

90. List the file system hd1, hd2 etc and what they are meant for?

Ans:

91. How will you see the hard ware errors?

Ans: # errpt –d –H

92. How to clear the all errorlog messages?

Ans:# errclear 0

93. How to make the secondary dumpdevice permanently active?

Ans: # sysdumdev –P –s /dev/xxx.

94. Tell me the steps to replace the one hdd belongs to the mirrored rootvg?

Ans. Explain the detailed procedure

95. What is the command to move an lv to another hdd?

Ans: # migratepv –l lv_name hdiskx hdisky

96. How to disable a user from remote login?

Ans: # chuser rlogin=false user_name

97. How to prevent all users to login from the remote?

Ans: # touch /etc/nologin (Except root all users can not login from remote)

98. How to add a pv into a VG?

Ans: # extendvg vg_name pv_name

99. How to see the ftp service is running or not? How to enable it?

Ans: lssrc –s inetd, startsrc –s inetd or startsrc –t ftpd

100. What are the differences between IPAT over IP aliasing and replacement?

Ans: Explained the complete details of both methods.

101. What is the difference between MOUNT=TRUE and MOUNT=AUTOMATIC in /etc/filesystems?

Ans: OS related File systems which are mounted at the time of boot process will have ‘AUTOMATIC’ attribute and other filesystem which can be mounted along with system startup

Will have ‘TRUE’ attribute.

102. What is sticky bit and tell me example?

Ans: Sticky bit permission will be set to directory so as all user can make use of the files in that directory, but only owner can delete the file.

103. What is setuid and tell me example?

Ans: A file which is having SUID will be excuted as if its effective id Eg. /etc/passwd

104. If T and S permissions are set for the files what does it mean?

Ans: When Sticky bit and SUID permission set on directory and file which are not with executable permissions  set  respectively will shown like this.

105. How to check a VG is mirrored or not?

Ans: If a lp is mapped to more than one  pp by  lsvg –l vgname  command then VG is said to be mirrored.

106. What are the differences between AIX 5.1 and 5.3?

Ans:

107. What is the difference between UDP and TCP?

Ans:TCP- Connection oriented and acknowledgment for packet transmitted.

UDP-User Datagram protocol- Connectionless and no acknowledgment for the packets transmitted.

108. How to restore a single file of rootvg from mksysb backup tape media?

Ans: restore –S4 xvf /dev/rmt0 ./<filename>

109. How to format a log file system?

Ans: logform <device name>

110. What is the difference between applied and committed s/w?

Ans: applied state software can be rejected if don’t work properly if it suite then it can be committed. A software which was committed can‘t be rejected only way is uninstall.

111. How to commit applied state software?

Ans: installp –cgX <fileset name>

112. What is the difference between hard and soft mount in NFS?

Ans: For Hard mount the client keep tries to mount the file system until it succeeds. Where as the Soft Mount tries to mount the file system for few attempts if it is not succeeded in a given attempts it gives up.

113. What is the command to make the hdisk as bootable (bosboot)?

Ans: bosboot –ad /dev/hd5.

114. What is the lpp resource in NIM?

Ans. It has software image to be installed at client.

115. How to list all file systems?

Ans: lsfs

116. How will you edit the crontab?

Ans:    crontab –e

crontab –l > filename, edit file and crontab filename.

117. How do you list all volume groups?

Ans. Lsvg

118. How do you mirror rootvg?

Ans. Extendvg rootvg hdiskn, mirrorvg rootvg hdiskn, bosboot –ad, bootlist –m normal hdiskx, hdiskn.

119. What are the commands you used for performance monitoring?

Ans. Vmstat, sar, iostat, topas etc.

120. How will you come to know the system required more real memory using vmstat?

Ans. If pi and Po count is more (if paging activity is more even though it has enough paging space)

121. What is the use of AT command and how will you list the jobs?

Ans: One time operation for a given time. Atq –L

122. How do you exclude some file systems while taking mksysb backup?

Ans: By mentioning the file systems name in exclude.rootvg

123. How do you list the pv in system?

Ans: lspv

124. What are the AIX installation methods?

Ans: Complete and overwrite, preservation installation and migration

125. What are the prerequisites before attempting migration installation?

Ans: Take the system backup, check for hardware and s/w compatibility for newly installable os. Prepare with remedies for known problems.

126. How to roll back to the previous ML level if the newly installed ML had problem with 

applications?

Ans: If newly installed ML is in applied state, reject it. If it is committed state remove the fix and reinstall the previous ML.

127. What are the difference between applied state and committed state?

Ans: If we select applied state it will not replace the previous level and will have option to commit or reject the newly installed s/w. In committed state newly installed s/w will overwrite the existing s/w and will not have option to reject.

128. What is /etc/filesystems and what is its role?

Ans: /etc/filesystem has information regarding file systems, its mount point type of file system etc. Its main purpose to mount and check the file systems as per the parameters mentioned in it.

129. How to see the paging space?

Ans: lsps –a

130. How to increase the paging space?

Ans: chps –s pp’s  devicename.

131. What is the default paging space device?

Ans: hd6

132. What is ODM & Location of Database Files?

Ans; ODM is database which contains the information of devices & system configuration. /etc/objrepos, /usr/lib/objrepos, /usr/share/lib/objrepos

133. Give details of each database files?

Ans: /etc/objrepos:  contains customized database

/usr/lib/objrepos:  contains predefined database

/usr/share/lib/objrepos:  contains software vital product data

134. How to set password history?

Ans: /etc/security/user

135. How to set two or three password?

 Ans:

136. What happens when execute exportvg & importvg?

Ans: Exportvg: removes info. of particular VG from ODM

  Importvg:  Add info. Of from VGDA of disk to ODM

137. What is NFS & file names of NFS?

NFS is distributed file system which provide remote access of file system.

File name:  /etc/exports

138. How to set permissions for exported directory?

Using /etc/exports

139. What are the types of Installation in AIX?

Ans: Complete/Overwrite Migration and Preservation Installation.

140. What is migration installation?

Ans:  For Upgrading the version of AIX.