NFS Services Administrator's Guide

Configuring and Administering NIS
Overview of NIS
Chapter 4148
• /etc/vhe_list, a configuration file for the Virtual Home
Environment. (Type man 4 vhe_list for more information.) VHE is
not supported on 10.0 and later releases.
The information in these files is put into NIS databases automatically
when you create an NIS master server. Other system files may be
managed by NIS, if you wish to customize your configuration.
Structure of the NIS Network
The center of the NIS network is the NIS master server. When you
create an NIS master server, the configuration files on that host are used
to create NIS maps, which are hashed database versions of the
configuration files. Once the NIS network is set up, any changes to the
maps must be made on the master server.
In addition to the master server, you can create backup servers, called
NIS slave servers, to take some load off the master server and to
substitute for the master server when it is down. When you create an
NIS slave server, the maps on the master server are transferred to the
slave server. Whenever a change is made to a map on the master server,
the modified map must be transferred to the slave servers.
Typically, all the hosts in the network, including the master and slave
servers, are NIS clients. Whenever a process on an NIS client requests
configuration information, it calls NIS instead of looking in its local
configuration files. (For group and password information and mail
aliases, the /etc files may be consulted first, and NIS may be consulted if
the requested information is not found in the /etc files.)
The set of maps shared by the servers and clients is called the NIS
domain. The master copies of the maps are located on the NIS master
server, in the directory /var/yp/domainname. Under the domainname
directory, each map is stored as two files: mapname.dir and
mapname.pag. Each slave server has an identical directory containing
the same set of maps.
When a client starts up, it broadcasts a request for a server that serves
its domain. Any server that has the set of maps for the client’s domain
may answer the request. The client “binds” to the first server to answer
its request, and that server answers all of its NIS queries.