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NOTE: This article was originally published on a previous project by jrf. It has gleaned for use here.

Overview of DNS

DNS came about quite simply because using hostname resolution was getting to be a severe burden. There was a "Master Host File" maintained at one time, unfortunately it simply got too big and cumbersome. Enter the Domain Name System. The Internet like any other Network has a hierachal structure to it. Both through IP address schema and Domain Name schema. For the sake of an example, let's say our domain is boogly.woogly.net . The .net is the root domain or top level of the network. Woogly is the Network Name and boogly is the hostname. In addtion to naming ( from right to left ) host.network.root you can also devise host.subnetwork.network.root which is extremely helpful in a large enterprise network. Many organizations breakup functions by sub-domain name.

The Database

The DNS Database is a collection of files formatted specifically for the purpose of Domain Name Resolution. The database does differ slightly on Primary and Secondary Nameservers. The files required for the Primary (or Master) Domain Controller are outlined below.

/etc/named.boot: This file tells the system (NT or UNIX) where to look for the DNS database. In accordance with the Bind Manual which can be downloaded from here , these files should be stored in the /var/named directory. An example of this file can be found at verinet ~ named.boot .
/etc/resolv.conf: This file is not required for operation but it is required if you want to do any lookups. The IP address of all of the nameservers on your network belong in this file. An example of this file can be found at verinet ~ resolv.conf .
/var/named/db.cache: This file holds information about root servers on the Internet that are needed to initialize the cache of the Internet Domain Name Servers. An example of this file can be found at verinet ~ db.cache.
/var/named/db.127.0.0: This file is a local host reference just like the local host reference line in the /etc/hosts table. An example of this file can be found at verinet ~ 127.
/var/named/192.222.180: This file is for reverse lookups. Upon looking at the format you will see that out of network addresses cannot be kept in this file. You may still, however, have hosts not in the same network within the same domain. An example of this file can be found at verinet ~ 192.
/var/named/db.mydomain.com: This is the most important and used file in the database. This file has all of the absolute domain names, their IP addresses and any alias' you may have for them. An example of this file can be found at verinet ~ mydomain.

Secondary Nameserver Files

The secondary nameserver requires an /etc/host/resolv.conf, a local host reference (db.127.0.0) and a db.cache exactly like the primary. The only major difference is the format of the /etc/named.boot file. The reason for that is this file points to the Primary Controller. An example of this file can be found at verinet ~ secondary.

Database Generation

Aside from Operating System Specific Methods, there are two ways to Generate the Database. The first way is the mind numbing process of building the databases from scratch. The second (and preferable) method is to use BIND tools to automatically generate the database from input you give it. This requires that you have the domain name and network address ready when you install it-and that you are positive you want the host to be a primary or secondary server.

Database Maintenance Rules

Surprisingly you will find yourself editing database files more often than you would like. There are some rules you must abide by when altering the database. Take special caution here, not unlike the Windows Registry Database, deviation from ANY of these rules will result in the database becoming corrupted. The only way to fix corruption is to regenerate the database.

Stay Within the format: Never under any circumastances attempt to not use the predefined tabs and spaces in the format of the database files.
Remember the Periods: Some entries require trailing periods. Make sure you use them. Errors with periods can be corrected if you abide by the next rule unwaveringly.
Increment the Database Files: Every time you edit a file, if it has a serial number, increment the serial number by one. Even if you are correcting a previous mistake. The serial number bascially let's other files know what "version" you are at.
Certain charachter's are illegal for use in Named, the underscore, for example may not be used as a domain name, however, some Operating Systems have a dirty hack around that for internal Named systems.

Intro Quality Only

This document is enough to get an internal single domain up and running (with the exception of specific automatic generation tools) but, for interaction with other nameservers (within or without of a corporate intranet) I strongly suggest visiting one of the sites listed at the bottom of the page.