System Admin Questions 5

Q: - How to detect CPU architecture/bitmode (32-bit or 64-bit) for Linux ?
# cat /proc/cpuinfo | grep flags

you will find one of them with name "tm(transparent mode)" or
"rm(real mode)" or "lm(long mode)"

1. rm tells ,it is a 16 bit processor
2. tm tells, it is a 32 bit processor
3. lm tells, it is a 64 bit processor

Q: - What is the difference between SSH and Telnet ?

The Primary difference between SSH and Telnet is of security i.e in ssh data transfer between the systems is in encrypted form so it is difficult for the hackers to understand what is going on network.

 In Telnet data transfer between the systems is in plain text. 

SSH uses a public key for authentication while Telnet does not use any authentication.

Due to the security measures that were necessary for SSH to be used in public networks, each packet contains less data to make room for the data of the security mechanisms. In order to transmit the same amount of data, you would need to take-up a lot more bandwidth. This is called overhead..

SSH adds a bit more overhead to the bandwidth compared to Telnet.

Q: - What is difference between AT and CRON?

Cron command is used to schedule the task daily at the same time repeatedly ,

at command is used to schedule the task only once i.e to run only one time.   

Q: - Which command is used to create LVM Snapshot?
vcreate --size -s -n

The lvcreate command is used to create a new logical volume, meaning there must be
free physical extents in the logical volume group to create a snapshot. The -s option
means that the LV is a snapshot, is the name of the new LV created, and
is the name of the LV from which to create the snapshot.

Q: - Is there any relation between modprobe.conf file and network devices?
Yes, This file assigns a kernel module to each network device.

For Example :-
[root@localhost ~]# cat /etc/modprobe.conf
alias eth0 b44

Here b44 is the kernel module for network device eth0.

We can Confirm by following command (This module “b44” is present or not).

[root@localhost ~]# lsmod |grep b44

b44                    29005    0

Q: - What is the location of "network" file and what does this contains?
location :-  /etc/sysconfig/network

This file contains following fields

NETWORKING=yes
NETWORKING_IPV6=no
HOSTNAME=localhost.localdomain

Q: - What is the role of /etc/resolv.conf file?
In this file we sets the DNS servers (using their IP addresses) and the search domain. The values of the DNS servers are often added when the network is activated because the data can be provided by DHCP or a similar service.

Q: - Which deamon is required to start Network services?
network

/etc/init.d/network start

Q: - What "neat" command will do?
neat command provides Graphical interface to change network settings for network devices.

Q: - Which protocol is required to allow local printing and print sharing?
Internet Printing Protocol (IPP) is required to allow local printing and print sharing.

Q: - What is CUPS?
CUPS stands for "Common UNIX Printing System". CUPS is a open source printing system developed by Apple Inc. CUPS uses the Internet Printing Protocol (IPP) to allow local printing and print sharing.

Q: -What is the location of log files for CUPS?
The log files for the CUPS printing system are located in the /var/log/cups/ directory.

Q: - What is YUM?
YUM stands for Yellow dog Updater, Modified because it is based on YUP, the Yellow dog Updater. Where does the name Yellow dog come from? Yellow Dog is a version of Linux for the Power Architecture hardware and is RPM-based, just like Red Hat Enterprise Linux and Fedora. YUP, and later YUM, were written by the Linux community as a way to maintain an RPM-based system.

Q: - What are the advantages of YUM?
- Automatic resolution of software dependencies.
- Multiple software locations at one time.
- Ability to specify particular software versions or architectures.

Q: - How you will install software by YUM?
yum install

Q: - Which option is required to assume the answer "yes" to any questions asked during installation of package dependencies for YUM?
The "-y" option is used to assume the answer "yes".

For Example

yum -y install squid

Q: - How to remove a software by YUM?
yum remove

Q: - How Many Run Levels present in Linux?
There are 7 run levels, with each having its own properties.

-   0: Halt the system
-   1: Single-user mode
-   2: Not used
-   3: Multi-user mode with text login
-   4: Not used
-   5: Multi-user mode with graphical login
-   6: Reboot

Q: - Which configuration file is required to change the Run Level of Server or system?
/etc/inittab

To change the default run level, modify this line.

id:5:initdefault:  

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