Network Information Service

The Network Information Service or NIS is Sun Microsystems' "Yellow Pages" (YP) client-server directory service protocol for distributing system configuration data such as user and host names between computers on a computer network. NIS/YP is used for keeping a central directory of users, hostnames and most other useful things in a computer network. For example, in a common UNIX environment, the list of users (for authentication) is placed in /etc/passwd. Using NIS adds another "global" user list which is used for authenticating users on any host.