Name Servers

In large installations, there are a number of different
collections of names that have to be managed. This includes users and
 their passwords, names and network addresses for computers, and
accounts. It becomes very tedious to keep this data up to date on all
of the computers. Thus the databases are kept on a small number of
systems. Other systems access the data over the network. (RFC 822 and
823 describe the name server protocol used to keep track of host names
and Internet addresses on the Internet. This is now a required part of
any TCP/IP implementation. IEN 116 describes an older name server
protocol that is used by a few terminal servers and other products to
look up host names. Sun's Yellow Pages system is designed as a general
mechanism to handle user names, file sharing groups, and other
databases commonly used by Unix systems. It is widely available
commercially. Its protocol definition is available from Sun.)