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<H1>Network Information Services</H1>
<P>
Network Information Services (NIS) is a popular name service that
centralizes network information in a database so that the information
can be easily administered and automatically propagated to other
servers in the network. The database contains name and address
information as well as information about network services. The
information originates in files that the NIS administrator maintains; 
these files are converted into a series of maps that compose the database.
</P>
<P>
Maps are stored in a hierarchy of NIS servers that respond to
information requests from NIS clients. The hierarchy consists of a
<EM>master server</EM>, which contains authoritative information, and
one or more <VAR>slave servers</VAR>, which contain copies of the
database. At least one server must exist on each network in the
organization to answer client queries. NIS master and slave servers
run the NIS server daemon, <VAR>ypserv</VAR>.
</P>
<P>
All systems that share a common database are in the same NIS domain. To
avoid confusion, NIS domains should correspond to DNS domains if you use
both name services.
</P>
<P>
<STRONG>Note:</STRONG> Because NIS is an insecure name service, it
should not be used on firewall systems or on any system containing
confidential data.
</P>
<P>To configure NIS, use these forms: </P>
<UL>
<LI><A HREF="index.nis1.shtml" TARGET="left">NIS Client</A>
<LI><A HREF="index.nis2.shtml" TARGET="left">NIS Master</A>
<LI><A HREF="index.nis3.shtml" TARGET="left">NIS Slave</A>
</UL>
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