System Admin Q & A – III

Ques 1: – What is the role of /etc/resolv.conf file ?

Ans: – 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.

Ques 2: – What is the difference between hardware RAID and Software RAID ?

Ans: – The hardware-based RAID is independent from the host. A Hardware RAID device connects to the SCSI controller and presents the RAID arrays as a single SCSI drive. An external RAID system moves all RAID handling “intelligence” into a controller located in the external disk subsystem. The whole subsystem is connected to the host via a normal SCSI controller and appears to the host as a single disk.

Software RAID is implemented under OS Kernel level. The Linux kernel contains an MD driver that allows the RAID solution to be completely hardware independent. The performance of a software-based array depends on the server CPU performance and load.

Ques 3: – What is the use of script command in Linux ?

Ans: – scriptcommand makes a copy (type script) of a terminal session. The most common use of script is to document terminal session. By starting script you can save all the information, displayed on your terminal during a login session, to a file. You can then print the file or view it with an editor. In a way script is a specialized tee for the shell.

When you run script a new shell is forked. This new shell makes a complete copy of everything displayed on your terminal. It reads standard input and output for your terminal tty and stores the data in a file. The default filename is typescript.

To exit from a script session you simply press Ctrl-D or type exit.
Format of the script command.

script [ -a ] [ typescript_file ]
Options
-a Append the output of script to file. Normally script begins writing to a new file; if the file exists it is overwritten unless you specify the -a option.

Ques 4: – Why should we use RAID ?

Ans: – System Administrators and others who manage large amounts of data would benefit from using RAID technology.
Following are the reasons to use RAID- Enhances speed
– Increases storage capacity using a single virtual disk
– Minimizes disk failur

Ques 5: – Can we create logs for ftp authenticated sessions?

Ans: – Yes, If the xferlog_enable directive in vsftpd.conf is set to YES, file transfers using the FTP protocol are logged to /var/log/xferlog. Information such as a time stamp, IP address of the client, the file being transferred, and the username of the person who authenticated the connection is included in the log entry.

Ques 6: – what is Stealth name server?

Ans: – Stealth name server is a secret server. This type of name server is not published anywhere. It is only known to the servers that have its IP address statically listed in their configuration. It is an authoritative server. It acquires the data for the zone with the help of a zone transfer. It can be the main server for the zone. Stealth servers can be used as a local backup if the local servers are unavailable.

Ques 7: – what is nmbd daemon?

Ans: – This daemon handles all name registration and resolution requests. It is the primary vehicle involved in network browsing. It handles all UDP-based protocols. The nmbd daemon should be the first command started as part of the Samba startup process.

Ques 8: – What is LMTP ?

Ans: – The Local Mail Transport Protocol (LMTP) is a different mail transport protocol described in RFC 2033. LMTP utilizes a set protocol similar to SMTP for delivering messages to the local host. Postfix can be configured to deliver messages to local users using LMTP if desired

Ques 9: – How you will put a limit on uploads on your web server?

Ans: – This can be achieved by LimitRequestBody directive.

LimitRequestBody 100000

Here I have put limit of 100000 Bytes

Ques 10: – How to Enable ACLs for /home partition?

Ans: -Add following entry in /etc/fstab

LABEL=/home /home ext3 acl 1 2

Now remount /home partition with acl option.

mount -t ext3 -o acl /dev/sda3 /home

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