NIS stores administrative information such as user names,
passwords, and host names on a centralized server. Client systems
on the network can access this common data. This configuration
allows to move from machine to machine without having to remember
different passwords and copy data from one machine to another.
Storing administrative information centrally, and providing a
means of accessing it from networked systems, also ensures the
consistency of that data. NIS also reduces the overhead of
maintaining administration files such as
/etc/passwd
on each system.
A network of NIS systems is an NIS domain. Each system within the domain has the same NIS domain name, which is different from a DNS domain name. The DNS domain is used throughout the Internet to refer to a group of systems. an NIS domain is used to identify systems that use files on an NIS server. an NIS domain must have exactly one master server but can have multiple slave servers.