understanding dns Server

DNS (Domain Name System) is a system that changes the host name (such as linux.or.id) into IP addresses (such as 64.29.24.175) on all computers connected directly to the Internet. DNS also can change the IP address into hostname.

DNS works in a hierarchical and shaped like a tree (tree). The upper part is a Top Level Domain (TLD) such as COM, ORG, EDU, MIL, etc.. Like the tree control have sought branches from the base to the tip. At the time we find an example linux.or.id first asked the TLD DNS server on the DNS server serving the domain. Id like answered ns1.id, after which he asked the ns1.id about the DNS server responsible for. Or . id like ns.or.id then he asked and answered ns.or.id about linux.or.id 64.29.24.175

Meanwhile, to change the IP hostname domain involves in-addr.arpa. Like other domains in-addr.arpa domain name any branching. The important thing is to remember its IP address written in reverse order under the in-addr.arpa. For example for the IP address 64.29.24.275 linux.or.id process as an example: find the server for ARPA, looking for the in-addr.arpa servers, search for 64.in-addr.arpa servers, search servers 29.64.in-addr.arpa , locate the server for 24.29.64.in-addr.arpa. And search for information 275.24.29.64.in-addr.arpa. Inverting the sequence of numbers can indeed be confusing.

DNS Server in Linux

DNS Server in Linux are usually run by a program called named. This program is part of the bind package coordinated by Paul Vixie of the Internet Software Consortium. Normally this program is located in / usr / sbin / named and run at boot time from / etc / rc.d / init.d / named start. To be named is run on every boot insert named to the list of servers that must distart using ntsysv.

Configuration Files
The configuration file for named is / etc / named.conf which as usual is a text file. This file format such as C or Pascal program format ie each command ends with ';' and block commands in parenthesis with '{' and '}'. There are some blocks that are often used, namely:

options
to set the global server configuration and determine the default
zone
to set the DNS zone configuration

Caching Only DNS Server

Caching Only DNS Server will find the answer to control and remember the answers when you ask again. This will shorten the waiting time in the next control question, especially if you are using slow connections such as modems.

Configuration
Caching-only DNS configuration file has been provided by Red Hat caching-nameserver package you just install the package and edit the file / etc / named.conf and add the following line in the block options:

    forward a first;
   forwarders (
     202.158.3.6;
      202.158.3.7;
   );