Tanti Technology

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Multi-platform UNIX systems consultant and administrator in mutualized and virtualized environments I have 4.5+ years experience in AIX system Administration field. This site will be helpful for system administrator in their day to day activities.Your comments on posts are welcome.This blog is all about IBM AIX Unix flavour. This blog will be used by System admins who will be using AIX in their work life. It can also be used for those newbies who want to get certifications in AIX Administration. This blog will be updated frequently to help the system admins and other new learners. DISCLAIMER: Please note that blog owner takes no responsibility of any kind for any type of data loss or damage by trying any of the command/method mentioned in this blog. You may use the commands/method/scripts on your own responsibility. If you find something useful, a comment would be appreciated to let other viewers also know that the solution/method work(ed) for you.

Thursday, 31 October 2013

Linux System Admin Interview Questions & Answers part 4

1.  What is the default UID when we are creating first user.(useradd)?
A: The first user created by root will always have a UID 500.
User ID=uid. The uid of root is 0.
UID from 1 to 499 is reserved for system services such as tha user apache,nagios,etc.

2. How many users are created by default.
A: Maximum users=60,000 by default.This could be increased.

3. Fields in password and shadow file.
A: Passwd file
Root:x:0:0:0:root:/root:/bin/bash
(username: encrypted form of password: uid: gid: personal info: home dir:shell)

4. When user is created which are the files it is updated.
A: /etc/passwd – contains various pieces of information for each user account
/etc/shadow – contains the encrypted password information for user’s accounts and optional the password aging information.
/etc/gshadow – group shadow file (contains the encrypted password for group)
/home –All users data is stored here.
/etc/login.defs---Shadow password suite configuration.

5. What is the owner of /tmp (is sticky bit applied on it)
A: drwxrwxrwt  11  root 20480 Apr 21 23:27 tmp (yes).

6. How to check which kernel module is installed?
A: modinfo-c
Also you can lok for the modules at:
Code:
/lib/modules
#rpm –qa  | grep ^kernel
#uname –r
#uname –rsv

7. What are modules,advantages and disadvantages of modules.
A: Modules are non-linked drivers.
Use of modules
Allow third party commercial development of drivers
Minimise kernel size
Allow smaller generic kernels
What is a Module
Contains device specific system routines
Fills in non-boot gaps in the kernel
Can be loaded and removed dynamically
Modules In Linux
Modules are compiled per Linux release
Multiple modules live in
/lib/modules//
Hence only the active version modules will load
Accept parameters.

15. How to check which disk is fault in hardware Raid level
A: # watch cat/proc/mdstat       -    Check RAID status
#mdadm /dev/md1 –fail/add/remove /dev/sda6 - For RAID partition fail,add & remove

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