The basic function of the name server is to provide information about network objects by answering queries. The specifications for this name server are defined in RFC1034, RFC1035 and RFC974. These documents can be found in /usr/src/etc/named/doc in 4.3BSD or ftped from ftp.rs.internic.net. It is also recommended that you read the related manual pages, named(8), resolver(3), and resolver(5).
The advantage of using a name server over the host table lookup for host name resolution is to avoid the need for a single centralized clearinghouse for all names. The authority for this information can be delegated to the different organizations on the network responsible for it.
The host table lookup routines require that the master file for the entire network be maintained at a central location by a few people. This works fine for small networks where there are only a few machines and the different organizations responsible for them cooperate. But this does not work well for large networks where machines cross organizational boundaries.
With the name server, the network can be broken into a hierarchy of domains. The name space is organized as a tree according to organizational or administrative boundaries. Each node, called a domain, is given a label, and the name of the domain is the concatenation of all the labels of the domains from the root to the current domain, listed from right to left separated by dots. A label need only be unique within its domain. The whole space is partitioned into several areas called zones, each starting at a domain and extending down to the leaf domains or to domains where other zones start. Zones usually represent administrative boundaries. An example of a host address for a host at the University of California, Berkeley would look as follows:
The top level domain for educational organizations is EDU; Berkeley is a subdomain of EDU and monet is the name of the host.