Path: utzoo!attcan!uunet!husc6!uwvax!rutgers!columbia!cunixc!alan
From: alan@cunixc.columbia.edu (Alan Crosswell)
Newsgroups: comp.protocols.tcp-ip
Subject: Re: Domain name/subnet relationship.
Message-ID: <747@cunixc.columbia.edu>
Date: 27 Jun 88 12:47:37 GMT
References: <8806270548.AA23542@ucbvax.Berkeley.EDU>
Reply-To: alan@cunixc.columbia.edu (Alan Crosswell)
Organization: Columbia University
Lines: 28

In article <8806270548.AA23542@ucbvax.Berkeley.EDU> RACKLEY@MSSTATE.BITNET (Mike Rackley) writes:
>I am confused about the relationship of domains and subnets.  Is there,
>or should there be, any specific relationship between domains and subnets?
>In particuar, is it possible to have a single domain that contains more than
>one subnet?  Conversely, is it possible to have a single subnet that contains
>more than one domain?  Can you have a single domain that is spread among
>several subnets?  The situation I am wondering about is where a department is
>spread among several buildings on campus.

Domains are basically a *user* convenience for naming an IP address.  There is
no required relationship between a domain name and an IP address, network,
subnet, campus, etc.  In usual practice they happen to correspond since
single departments tend to be on a single subnet.  However, it is perfectly
reasonable to have members of the same subdomain be located on radically
different networks (e.g. on opposite sides of the world).  You just better
hope that a domain name server for that domain is reachable from both those
networks (not necessarily the same one!).

A lot of people get domains and networks locked together in their
minds mainly as a result of poor examples of domain usage like .BITNET
and .UUCP where the domain is actually being used to indicate a
specific non-IP network.  Work is progressing in both these networks
to convert to proper domain names.  There are now many "MX" servers on
the Internet that respond to domain lookups for BITNET and UUCP
hosts.

Alan Crosswell
Columbia University