The Network Information Service (NIS) is a system that provides network information (login names,
passwords, home directories, group information) to all of the machines on a network. NIS can allow
users to log in on any machine on the network, as long as the machine has the NIS client programs
running and the user’s password is recorded in the NIS passwd database. NIS was formerly known as
Sun Yellow Pages(YP). This NIS implementation is based on FreeBSD’s YP and is a special port for
glibc 2.x and libc versions 5.4.21 and later. This package only provides the NIS client programs. In
order to use the clients, you need to have an NIS server running on your network. An NIS server is
provided in the ypserv package. Install the yp?tools package if you need NIS client programs for
machines on your network. You will also need to install the ypbind package on every machine
running NIS client programs. If you need an NIS server, you need to install the ypserv package on one
machine on the network.

Sumber : http://www.tldp.org/LDP/Linux?Dictionary/html/index.html