To specify the domain name of a computer:
This is the domain where your host resides, including all subdomains and the root domain, separated by periods.
The domain name is also part of a fully-qualified host name. In the fully-qualified host name:
poe.eng.mit.edu
the domain name is eng.mit.edu.
As an alternative to specifying a domain name, you can specify domains to be searched in the LAN Domain Search List field. If you specify both a local domain name and domains to be searched, the LAN Domain Search List will be used exclusively.