AIX Administrator Interview Questions and Answers

July 15, 2016 by S4

Filed under AIX, Unix

Last modified July 26, 2016

AIX Administrator Interview Questions and Answers

1. A company’s current server configuration (which is also sufficient for the software installed )is :
hard disk =10GB
memory =512
The division is planning to expand rapidly and users are expected to double in size within six months. What server should the division start with:
a> 2 processors, 1GB memory, 20GB hard disk space
b> 4 processors, 1GB memory, 10GB hard disk space
c> 1 processors,512mb memory,40GB hard disk space
d> 3 processors,512mb memory,40GB hard disk space
ans: a

2. A multinational finance company has approved a new package that runs on RS6000. The old data has to be converted to a new system. Currently they have 10gb of data but will be growing to 18 GB with the new system because they want to maintain 1 Year history online.The new system has 512 ram ,an ssa card, two 9.1 gb ssa drivesa and a fddi card. What will be the best addition to this system for redundancy?
1> One ssa card
2> Two 9.1 gb ssa drive
3> error correction ram
4> two additional processors
a> 1,2
b> 4,1
c> 4,2
d> 3,1
answer:a

3.Command to reject applied software?
ans: installp -r

4. What is the best way to remove the trusted base computing system once it is installed?
ans: reinstall the system without the trusted computing base option

5. During a preservation install, the administrator would like to maintain the files in /var directory.
What should be done to prevent the /var directory from being overwritten?
ans: Update the /etc/preserve.list with the files to be saved in the directory

6. An administrator is facing paging space problems in his system. The server has 120 mb of physical ram. How big should the paging space be , to alleviate this issue?
ans: The paging space size should be atleast 240 mb

7. Sys admin would like all users who telnet to the server to get a specific login message. Which file should be edited for this purpose?
ans: /etc/motd

8. to view a list of files associated with a particular product :
ans: do lslpp -f product name

9. A company would like to install a third party product called Performance tool. Upon trying to install the product , the sys admin receives an error indicating that the prereq software BASEPROD.NET is missing. This is located in another CD. when the admin tries to install that first,it fails and gives an error stating that Performance tool is missing. Which of the following approaches would assist in solving this problem?
a> copy both products to a directory and install from there
b> go back to the first cd and try installing performance tool from there
c> Install base.prod.net and then switch cds during installation
d> get another cdrom and install both the cds at the same time
ans:a

10. A new software disabled some critical functions of the system. The software has been applied but not committed. The system admin has already created a file a.txt that contains all the filesets to be rejected. What is the command to reject the software?
a> installp -rBX -f a.txt
b> installp -uBX -f a.txt
c> instfix -rgX -f a.txt
d> instfix -ugX -f a.txt
ans: a

11. To verify if a specific APAR has been installed by the sys admin, run the command:
a> fsck -y
b> instfix -ik
c> chkfix -all
d> lslpp -f
ans:b

12. system admin put updates and patches in an install directory. However a collegue cannot see an update in the smit listing even though the sys admin is sure that that copies of images are out there Which of the foll commands were not issued:
a> reexport of filesystem
b> Touch the signature file in the install directory
c> Run “inutoc” on the directory containing the image
d> Run “installp -qld” on the directory to make the images available
ans: c

13. A system admin needs to remove some updates to some third party software. The admin needs to put the filesets back to the original , before the update was installed. Unfortunately the update has been already committed..The administrator is trying to reinstall with least amount of software. Which command should be used to updates the product?
a> verifylp -rB
b> removelp -rg
c> installp -uB
d> uninstallp -ug
ans: C

14. APARS and PTFs are available online thro which utility?
ans: fixdist

15. To upgrade from aix 4.3 to 5.1 , what should be done?
ans: Boot from installation cd

16. A coworker accidently erased the /project/current directory which is located in the root volume grooup. A mksysb was done the earlier day. Once tape is rewound, which command should be issued?
a> tar -xvf /project/current
b>dd if =rmt0 of=/project/current
c> cpio -v -d restore -x -d -v -s4 -f/dev/rmt0.1 ./project/current
ans : d

17.To check all the available drives and devices on the system?
ans: lsdev -C -H

18.To delete a print job(JOB ID : 201) in the pcl queue,which command has to be issued?
ans: Cancel 201

19. A system has crashed and upon bringing the system back, the admin notices a huge print job has been spooled.the system admin has been able to disable the printer, but a third party software keeps enabling it. . The admin tries to cancel the job, but the crash corrupted the cancel command. what is the alternate way to cancel the queued job?
a> Turn off the printer and turn it back on
b> Run cancelall command
c>Uninstall the third party software that keeps enabling the printer
d> delete the correct file in the /var/spool/lpd/qdir directory
ans:d

20. Target machine has an IBM 3151 Terminal and no graphic capabilities. To prevent this message from appearing what action should be taken.
****Starting desktop Login on display :0? ** Wait for the Desktop login screen before loggin in ****888888888888
a> Run the cdecfg -disable command
b> Run the startx -no command and reboot
c> Run the dtconfig -d command and reboot
d> Remove the X=start line from the /etc/security /login.cfg and reboot
ans:d

21. command to determine the serial port settings:
ans: lsattr -El ttyxx

22. command to restart qdaemon?
ans: startsrc -s qdaemon

23. a system has a 9.1gb ultra scsi se disk and other 18.2gb differential disk. On rebooting, the system admin notices only the SE disk is available. Which is the most likely cause?
a> the scsi conflict between two drives
b> se and differential drives are on the same chain
c> se disk is probably experiencing the hardware prob
d> differential disk is experiencing hardware prob
ans:b

24. While using the smit install menus to install an LPP,the response “yes” has been selected to the option: EXTEND file systems if space needed. After successfully installing the lpp, the sys admin notices the /tmp filesystem is now unnecessarily large. Which of the foll actions will reduce the size of /tmp filesystem
a> backup , unmount ,recreate and restore filesystem
b> Unmount , run defrag and reduce size
c> Boot from mksysb tape and follow the procedure to reduce the filesystem
d> Update /etc/filesystems file with desired size for /tmp adn reboot
ans:c

25. command to determine if the upgrade from 4.3.2 to 4.3.3 was succesfully completed?
ans:oslevel …check oslevel reported
:if it still shows 4.3.2, then do an oslevel -l 4.3.3.0 to check which filesets were not upgraded

26. How will you remove an old software which is shown to be in commit state when you run lslpp command?
a> reinstall os
b>remove committed software thro smitty
c> Use smit_reconfig option to change the state to OPEN
d> Remove the lpp directory from the root
ans: b

27. Where would a failing disk drive information be revealed?
a> lspv
b> errpt
c>syslog
d> /var/adm/messages
ans: b

28. Which command can detect the sluggish running of a system , to provide realtime display of CPU,memory and disk utilization
a> /usr/bin/lpp
b>/usr/bin/topas
c>/usr/bin/vmstat
d> /usr/sbin/monitord
ans:b

29. The sys admin has just finished upgrading a system to aix 5l. in case there is any future problems, the sys admin would like to add an entry to the AIX errorlog

recording this event. what command can be issued to accomplish this?
a> /usr/bin/errmsg”System upgraded to aix 5l”
b> /usr/bin/errlog”System upgraded to aix 5l”
c> /usr/bin/errupdate”System upgraded to aix 5l”
d> /usr/bin/errlogger”System upgraded to aix 5l”
ans: d

30. given the output of the errpt command:
Identifier timestamp tc resource name description
B654e890 062490000 TH rmt0 tape operator error
what command would display this info about this error?
a> diag -t -h
b>lsdev -C -l rmt0
c> errmsg -i B654e890
D> errpt -a -j B654e890
ans:d

31. To list all the fixes that can be installed on the aix server from a fix cd-rom
a> lslpp -T -l -d/dev/cd0
b> instfix -T -d/dev/cd0
c> listfix -l -d/dev/cd0
d> installp -T -l -d/dev/cd0
ans:b

32. how will you gracefully reboot a server?
ans: shutdown -r

33. What levels of AIX have you worked with?
ans: AIX 4.3.3 and AIX 5.1 good
If only AIX 4.2.1, 4.1, or 3.2, bad

34. What types of machines have you worked with?
ans: Look for questions pertaining to the hardware, to ascertain level of competence and understanding.
Take note of applicants who mention older technologies like “SP2” or newer technologies like “Regatta”

35. What applications have you used with AIX?
ans: Look for applications like HACMP, ADSM/TSM, SAP, i2, Manugistics, MQ Series, WebSphere, etc.
An applicant with considerable HACMP experience is likely to have quite a bit of AIX knowledge, especially LVM, disks, general TCPIP, and application enablement.

36.Suppose that there are some users that need to run certain commands normally only accessible by root. How would you grant them access?
ans: sudo

37: Discuss your philosophy on granting user access to root or to an application user ID.
ans: For root, prefer to

38. The system is performing very slowly; you have discovered that this is due to an increasing number of defunct processes are being created. How can you determine the cause?
ans:
1. Check to see if new defunct processes are being created, owned by the init process, with no processes being deleted at all.
2. If some defunct processes are being cleared out and the overall number of defunct processes is still growing, then this is due to an application creating more defunct processes than the init process can clean out.
3. However, if NO defunct processes owned by init (PID 1) are being cleared out, this points to an incorrect wait entry in the /etc/inittab file. The init process is stuck on this wait entry and will not cycle through the defunct processes until that entry finishes. The solution is to change that “wait” entry to a “once” entry.

39.You get a message that the system can’t fork any additional processes? What do suspect to be the problem?
ans: Either paging space is full or maxuproc (maximum number of user processes) is set too low.

40. You’re running some commands and getting an error that says “srcmstr daemon is not running”. Obviously, it is, because the machine appears to be functional. What is the likely cause?
ans: Someone has updated some of the base kernel filesets without rebooting the machine.

41. Describe one situation where it might be appropriate to edit the ODM.
ans: E.g., need to make parameter changes to a device that is open, and that cannot be modified without closing the device (i.e., a network device), and where the machine can be easily rebooted following the change.

42. Describe how to manually edit the ODM. What commands should be used?
ans: Use the odmget command to grab the appropriate entries from the ODM, into a text file.
Edit these entries.
Use the odmdelete command to delete the current entries.
Use the odmadd command to add the new entries.
If these are device configuration files, use the savebase command to save them into the boot image.

42. When might the savebase command be used?
ans: After making manual changes to the CuAt, CuDv, CuDvDr, CuDep, or CuVPD ODM classes (aka the device configuration database), these classes must be saved into the boot image in the boot logical volume. If they are not saved, there is a risk run that the changes won’t be saved at boot. Note that the chdev command (and others) will cause savebase to be run.

43. What key would you use at boot time to signal the machine to boot into service mode?
ans: F5 or 5 will signal the machine to boot from the internal boot list. F1 or 1 will bring the machine into SMS mode. The F[x] keys are used for graphical consoles; the others are used on ASCII consoles.

44. What is the effect of setting the normal mode bootlist to cd0 first and hdisk0 second?
Answer: The machine will boot from the CDROM into maintenance mode automatically if a boot CD has been inserted. If not, the machine will boot from the disk into normal mode.

45. A machine hangs at boot because the network is inaccessible or an NIS server is accessible. How can you recover?
ans: With inaccessible network (LED 581 for a long time), the machine will generally recover after timing out. With a NIS problem, probably have to boot into service mode

46. What’s the difference between RAID-0 and RAID-1?
ans: RAID-0 is hardware striping. RAID-1 is mirroring.

47. When using an SSA array, what are the tradeoffs to consider between using a large RAID-5 array and using LVM mirroring?
ans: RAID-5 would waste fewer disks, but it would be slower.

48. How do you properly mirror rootvg to protect the OS from crashing should a disk fail?
ans: Use the mirrorvg command to mirror the logical volumes
Run the bosboot command to reboot the boot image and update the disk boot record on both disks that contain a copy of the boot logical volume.
Run the bootlist command to add both disks to the boot list.
Mirror all non-rootvg paging spaces as well as those in rootvg.
Dump device?
Paging space?

49. Why is it important to mirror non-rootvg paging spaces, and what might be the effect if this is not done?
ans: The OS allocates pages in a round-robin fashion across all paging devices. If a non-rootvg disk containing a paging space fails, the system will likely crash unless it is mirrored. Putting paging spaces on RAID disks is not recommended due to the performance implications.

50. What kind of considerations can be made with regard to mirroring rootvg in a non-mission critical environment where maximizing disk space is important?
ans: You might be able to get away with not mirroring any paging spaces, the boot logical volume, or any non-critical file systems. If a disk crashes, you might have to perform some maintenance in service mode.

51. Provide the steps to move a file system from one volume group to another WITHOUT recreating and restoring it.
ans: Unmount the file system
Use the cplv command to copy the logical volume to the new volume group.
Use the chfs command to update the dev and log entries for the file system.
Run fsck.

52. Why is directly editing /etc/filesystems, to change information for a file system, a bad idea?
ans: The entries from /etc/filesystems are usually stored in the logical volume control block for each logical volume. If you ever had to run importvg for this volume group (i.e., after a reinstall or if using HACMP), the changes would be lost.

53. You can’t unmount a file system (AIX says it’s in use). How do you determine what process is keeping it open?
ans: fuser or lsof.

54. The “df” command shows that the file system is 100% full, but “du” shows no files in the file system. Why, and how do you debug this?
ans: A running process is holding open a file descriptor that references a large amount of space either not saved as a file or references a file that has been deleted. Use “lsof” or “fuser” to track down this process.

55. The “df” and “du” commands indicate that the file system is 50% full, but you notice that the total size of all files, as given by “ls” is greater than the size of the file system. How is this possible?
ans: These are sparse files, where the size of the file is larger than the amount of space it takes up. The file contains a large of “null blocks”.

56. What steps should you follow to replace a failed hdisk?
ans: Remove all allocated logical volumes (if not mirrored) or LV copies (if mirrored).
Remove disk from the volume group.
Remove disk definition (and pdisk, if it’s an SSA drive mapped 1-to-1)
Physically replace disk
Run cfgmgr.
Add disk to volume group and recreate LVs or LV copies.

57. Basic network configuration
ans: “smit mktcpip”?

58. What file is used to tell AIX to use local /etc/hosts entries instead of DNS?
ans: /etc/netsvc.conf. Specifically, the entry is “hosts=local,bind”.

59. There is a conflict between a machine’s IP address and the DNS entry. Unfortunately, the DNS server is a Win2K server managed by a little old lady who works once a week. How do you get around this?
ans: Put an entry in /etc/hosts, and then use /etc/netsvc.conf to force AIX to read /etc/hosts first.

60. You’ve properly exported a file system on a server. You’ve properly set up the NFS file system definition on the client, and the proper daemons are running. However, when you try to mount it, you get an error:
mount: 1831-009 aixnim not in hosts database
mount: 1831-008 giving up on:
aixnim:/nim
A route to the remote host is not available.
What two options do you have to resolve this?
ans: Check /etc/resolv.conf for an entry to the appropriate nameserver.
Add it to /etc/hosts.

61. What is resolv.conf used for?
ans: To provide a list of nameservers and domains to search for hosts.

62. Your machines are in the xyz.com domain. You want to be able to look up hosts in the abc.com domain. What should you do so that the ping command will find a route to those hosts?
ans: Add the nameserver for that domain to /etc/resolv.conf.
Make sure you have a route to those nameservers.

63. Where is the default gateway stored in AIX? Where are other routes stored?
ans: As ODM entries in the CuAt ODM class.

64. A project manager claims that a system is CPU-bound. What commands do you run to verify this, and what sort of output are you looking for?
ans: Run vmstat and look at the wait, idle, CPU utilization, runq and blockq parameters.
A CPU-bound system will exhibit relatively low wait and idle percentages and a high degree of CPU usage.
In addition, the runq parameter will average the number of CPUs on the system and the blockq parameter will be, on the average, high.

65. You have a 32-way Regatta. Why is vmstat not an accurate tool to measure CPU utilization for each processor?
ans: vmstat takes a system average. The sar command can show the CPU utilization for a particular processor.

66: If you have Workload Manager policies defined for several classes of processes, and the machine is under little load, whatell which files are provided?
ans: Run “lslpp -f ” to see what files are installed by that fileset.

67. What are the AIX Maintenance Levels and how do they differ from normal fixes?
ans: AIX Maintenance Levels are similar to an NT service pack. They are generally considered safe to install “all at once”. Normal AIX fix collections may or may not contain fixes that could interfere with each other; however, maintenance levels are generally considered safe.

68. Describe the difference between a PTF, and APAR, and a maintenance level.
ans: An APAR is a specific patch that may update one or more filesets. A PTF is an IBM term for a collection of APARs commonly shipped together as a common fileset update. A maintenance level is a collection of APARs (also generally ordered as an APAR).

69. Your machine is running AIX 4.3.3 with maintenance level 10 applied. “oslevel” (no option) reports “4.3.2.0”. Why?
ans: There are some filesets installed that are at a level BELOW what is defined for 4.3.3.

70. What is the difference between applying and committing an APAR?
ans: Applying it saves the old versions of the files so that you can back off the new version. Committing the APAR removes the old versions.

71. How do you back off a committed set of patches?
ans: You have to forcibly install the base level of the affected filesets, while NOT reinstalling any prerequisites, and then re-patch back to the appropriate level.

72. You’re installing a new IBM 6228 fiber card into an existing 4.3.3 system for the first time. What problems might you encouter?
ans: The AIX 4.3.3 CDs don’t provide any base support for IBM 6228 fiber cards. You must download the drivers in the form of an APAR and install them separately. AIX 5.1 provide fiber support in the base CDs.

73. A group of developers wants to know if they will be able to install different versions of the Java runtime on a machine. Specifically, they want to install the base level filesets for versions 1.2.2, 1.3.0, and 1.3.1, as well as a separate set of patches. What do you tell them?
ans: JDK/JRE 1.2.2, 1.3.0, and 1.3.1 can all coexist on a machine, as they are completely separate sets of filesets. However, patches for these versions cannot coexist with the base levels.

74. Versions 3.6.4 and 3.6.6 of the IBM CSet++ compiler are comprised of the same basic set of fileset names, meaning that they normally cannot be installed on the same machine at the same time. What solution (unsupported by IBM) do you suggest? What considerations must you give to this environment?
ans: Install the second set of software on a second machine. Take all the files installed by those filesets and copy them to the other machine into another directory. The ODM will not recognize that the second set of filesets are installed, but the product will still be functional. Note that this is unsupported by IBM, but there’s a fine line between “unsupported” and “functional”. Note that you can’t very easily apply patches to this environment.

75. What does the LIBPATH variable do?
ans: It controls the order in which libraries will be discovered so as to arbitrate between libraries with the same name.

76. When IBM some particular sequence of commands or environment is “not supported”, what do they mean?
ans: That it may work, but that won’t SUPPORT it because they haven’t TESTED it.

77. An AIX installation has just completed. Maintenance Level 6 has been applied to the BOS.Which command will show all installed maintenance levels concurrently?
(a) oslevel -a
(b) lslpp -l | grep AIX
(c) smitty show_apar_stat
(d) instfix -ik | grep AIX
ans .D

78. What is the purpose of the -i flag with the mksysb command?
(a) It creates/updates the /.fsdata.
(b) It reports the size of a file in bytes.
(c) It creates a bootable system backup.
(d) It creates or updates the /image.data file.
ans. D

79. The system administrator would like to log messages related to user login failures to a file. How could this be accomplished?
(a) Issue the command: alog -f /etc/security/failedlogin -q .
(b) Modify the /etc/security/login to add an auth_method for logging.
(c) Add a line to the /etc/syslog.conf file to capture this information.
(d) Set “log=true” in the default stanza in the /etc/security/user file.
ans .C

80. How would an administrator verify that the system has all required prerequisite fixes prior to installing a software fix?
(a) Use the lsprereq command.
(b) Use installp with the preview option.
(c) View the .toc file in the root directory.
(d) Use the inutoc command to update the .toc file.
ans .B

81. The Widget Company has installed a new laser printer on their network. The RS/6000 has been configured to print to that printer via the “pcl” queue. A print job was submitted to the “pcl” queue and was running until the printer ran out of paper. The printer was offline for 30 minutes before the paper was added. What needs to be done to continue the print job?
(a) enable pcl
(b) startsrc -s lpd
(c) refresh -s lpd
(d) resubmit the job
ans .A

82. A system administrator’s daily monitoring has revealed a failing disk drive. While examining the system, the administrator identified an unallocated drive. Which of the following actions should be performed first in order to migrate the data from the failing drive to the unallocated drive?
(a) Migrate logical volumes to the new drive.
(b) Add the unallocated drive to the volume group.
(c) Create a copy of the filesystems to the new drive.
(d) Create a mirror of the logical volumes to the new drive.
ans .B

83. While using the smit install menus to install an LPP, the response “yes” has been selected for the option: EXTEND file systems if space needed. After successfully installing the LPP, the /usr filesystem appears to be unnecessarily large. Which of the following actions can be performed to reduce the size of the /usr filesystem?
(a) Backup, unmount, remove, recreate and restore the filesystem.
(b) Unmount, run defragfs /usr and the reducefs -size XXX /usr commands.
(c) Boot from mksysb tape and follow the procedure to reduce the
filesystem.
(d) Update /etc/filesystems with the desired size for /usr and reboot the
system.
ans. C

84. During bootup, the support specialist notices LEDs alternating between 223 and 229. This indicates an invalid boot device. Assuming no hardware failures, which of the following commands should be used next in order to determine the boot device once in a maintenance shell?
(a) lslv -m hd5
(b) lspv -m hd5
(c) bosboot -a -d hd5
(d) bootlist -m normal hd5
ans .a

85. After a power failure, the system attempts to reboot but hangs on 557. This indicates file system corruption. Which of the following actions should be taken to

recover?
(a) restore /etc/filesystems from mksysb
(b) execute chfs -a size=+1 against all filesystems in rootvg
(c) from a maintenace shell, run lppchk -v against all filesets installed
(d) from a maintenance shell, run fsck -y against all filesystems in rootvg
ans D

It has been determined that fix IX39714 needs to be applied to a server as soon as possible. How can this fix be obtained if the system has Internet connectivity?
86.
(a) Use the fixdist utility to download the fix.
(b) FTP the fix from fixes.pseries.ibm.com.
(c) Send an E-mail to “fixes.pseries.ibm.com” with “IX39714” in the subject
line.
(d) Use the Web-Based System Manager to download the fix.
ans. A

87. How would I know if my system is capable of using Simultaneous Multi-threading (SMT)?
ans: Your system is capable of SMT if it’s a POWER5-based system running AIX 5L Version 5.3.

88.How would I know if SMT is enabled for my system?
ans: If you run the smtctl command without any options, it tells you if it’s enabled or not.

89. Is SMT supported for the 32-bit kernel?
ans: Yes, SMT is supported for both 32-bit and 64-bit kernel.

90. How do I enable or disable SMT?
ans: You can enable or disable SMT by running the smtctl command. The following is the syntax:
smtctl [ -m off | on [ -w boot | now]]
The following options are available:
-m off Sets SMT mode to disabled.
-m on Sets SMT mode to enabled.
-w boot Makes the SMT mode change effective on next and subsequent reboots if you run the bosboot command before the next system reboot.
-w now Makes the SMT mode change immediately but will not persist across reboot.
If neither the -w boot or the -w now options are specified, then the mode change is made immediately. It persists across subsequent reboots if you run the bosboot
command before the next system reboot.

91.How do I get partition-specific information and statistics?
ans: The lparstat command provides a report of partition information and utilization statistics. This command also provides a display of Hypervisor information.

92.How do I determine the amount of paging space allocated and in use?
ans: Type the following:
lsps -a

93.How do I increase a paging space?
ans: You can use the chps -s command to dynamically increase the size of a paging space. For example, if you want to increase the size of hd6 with 3 logical partitions, you
issue the following command:
chps -s 3 hd6

94.How do I reduce a paging space?
ans: You can use the chps -d command to dynamically reduce the size of a paging space. For example, if you want to decrease the size of hd6 with four logical partitions.

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