Configure Host Header Names in IIS 5.0
To configure host header names in IIS, start the Internet Service Manager (Iis.msc)>the
Properties of the web, select IP address that the site will use and TCP Port
that should be used (usually 80). Click Advanced>Multiple identities for this
Web Site list, select the identity that you want to use. Click Edit, and then
add the desired host header name like web1.domain.com. Register the host
header name with the appropriate name resolution system. If the accessed web
is on an intranet register it with the intranet's name resolution system, such
as WINS and internal DNS. If the access web is on the Internet, register the
host header name with DNS, which is administered by InterNic.
NOTE: If you want this site to respond to more than one host header name, use
the Add button to add additional identities to this list. Specify a different
host header name for each identity, but be sure to use the same IP address and
port.