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DNS Tutorial

Remember that the machine which is a pure client, should not run the server daemon (“named” discussed below) but slave server can have both server and client process running in their Linux box.

DNS Server Setup

“named” description: For running a proper DNS server a daemon should run something called ‘named daemon’. It merely refers to the names of the machines rather than their ipaddresses. For this, the mapping name should be resolved by a server called ‘name server’. In order to run a `name server’, named daemon is needed. The files needed for configuring and running DNS (master and slave server) are:

1) /etc/named.conf

2) /var/named (remember its not file it’s a directory where the main database stays)

3) dnsconf utility

Before starting configuration by dnsconf utility lets see what actually the DNS server needs to get configured. It needs the following:

named configuration file (/etc/named.conf): It basically defines the parameters that point to the sources of domain database information, which can be local files or on remote servers.

Hint file (cache file)(/var/named/named.ca): It actually provides the name of root server which gets activated in case the machine name, which is to be searched, is not there in user defined zone (discussed below).

localhost file (/var/named.local): All configuration have a local domain Database for resolving address to the host name localhost.

Zone: Basically a zone that keeps the information about the domain database.

Later in named.conf file we will find that there are two predefined zones --named.local and named.ca --with database of localhost and database of root servers respectively. But zone needs another two files with Ipaddress to hostname mapping and hostname to Ipaddress mapping. The first one is called as Zone File and the second Reverse Zone File.

Zone file: The zone file defines most of the information. It is used to map host names to address, to identify the mail servers, and to provide other domain information.

Reverse Zone file: This is responsible for mapping Ipaddress to host names, which is exactly the opposite of what the zone file does.

Note that the above two files have to be user defined.

Now let us configure the master server with a proper example.

Example: Taking the above case of kshounish1.bigleap.com to kshounish10.bigleap.com, lets start with dnsconf.