The Network Information Service (NIS) was developed independently of DNS. DNS makes communication simpler by using machine names instead of numerical IP addresses. NIS focuses on making network administration more manageable by providing centralized control over a variety of network information. NIS stores information about the network, machine names and addresses, users, and network services. This collection of network information is referred to as the NIS namespace.
NIS namespace information is stored in NIS maps. NIS maps were designed to replace UNIX /etc files, as well as other configuration files. NIS maps store much more than names and addresses. As a result, the NIS namespace has a large set of maps. See Working With NIS Maps for more information.
NIS uses a client-server arrangement which is similar to DNS. Replicated NIS servers provide services to NIS clients. The principal servers are called master servers, and for reliability, the servers have backup, or slave servers. Both master and slave servers use the NIS retrieval software and both store NIS maps. For more information on NIS Architecture and NIS Administration, see Chapter 5, Setting Up and Configuring NIS Service and Chapter 6, Administering NIS (Tasks).