One of the oldest and best known distributed administrative database systems is Sun’s Network Information Service (NIS). It was superseded years ago by NIS+, an enhanced but more complex successor to NIS, also by Sun. More recently, LDAP (Lightweight Directory Access Protocol) servers have become more popular, and Sun users are migrating to LDAP-based services. However, even though NIS has been deprecated by Sun, it is still widely used in many environments. As such, it is worth describing.
NIS is a distributed database system that lets many computers share password files, group files, host tables, and other files over the network. Although the files appear to be available on every computer, they are actually stored on only a single computer, called the NIS master server (and possibly replicated on a backup, secondary server, or slave server ). The other computers on the network, NIS clients, can use the databases (such as /etc/passwd) stored on the master server as if they were stored locally. These databases are called NIS maps.
With NIS, a large network can be managed more easily because all of the account and configuration information (such as the /etc/passwd file) can be stored and maintained on a single machine yet used on all the systems in the network.
Some files are replaced by their NIS maps. Other files are augmented. For these files, NIS uses the plus sign ( +) to tell the client system that it should stop ...