By running NIS, the system administrator can distribute administrative databases, called maps, among a variety of master and slave servers. The administrator can update those databases from a centralized location in an automatic and reliable fashion to ensure that all NIS clients share the same naming service information in a consistent manner throughout the network.
NIS was developed independently of DNS and has a slightly different focus. Whereas DNS focuses on making communication simpler by using machine names instead of numerical IP addresses, NIS focuses on making network administration manageable by providing centralized control over a variety of network information. NIS stores information not only about machine names and addresses, but also about users, the network itself, and network services. This collection of network information is referred to as the NIS namespace.
NIS uses a client-server arrangement. NIS servers provide services to NIS clients. The principal server is called a master server, and for reliability, it can have several backup servers or slave servers. Both master and slave servers use the NIS information retrieval software, and both store NIS maps.
The following figure shows a domain that has unidentified hierarchical structure.
Figure 9 Domain with Unidentified Hierarchical Structure
The following figure shows how to arrange a physical network into a NIS domain.
Figure 10 Domain with NIS Namespace
An NIS domain cannot be connected directly to the Internet using just NIS. However, organizations that want to use NIS and also be connected to the Internet can combine NIS with DNS. You can use NIS to manage all local information and use DNS for Internet host lookup. NIS also provides a forwarding service that forwards host lookups to DNS if the information cannot be found in an NIS map. You can set up the name service switch in a Oracle Solaris system so that hosts lookup requests can be directed in the following ways:
To access only DNS
To access DNS, but if a host is not found in DNS, then access NIS
To access NIS, but if a host is not found by NIS, then access DNS
For maximum interoperability, DNS is the recommended service for host lookups. For more information, see About the Name Service Switch.