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domain name is a synonym? Well, I suppose in some circumstances. But...I don't know that it should be listed as anything other then ===See also===. A hundred hostnames could be hiding behind a NAT, in a server farm, for a single domain name. --Connel MacKenzie T C 06:51, 18 June 2006 (UTC)[reply]

It's not what's hiding behind a firewall, it's that every computer reachable by the Internet (as opposed to those that can just reach into the Internet) has a domain name, and that name is it's hostname. NAT came late to the game and server farms are a similar orthogonal issue.
Back in the early days each computer on the Internet had a hostname. Then came Flag Day, Jan 1 1983 -- the introduction of TCP/IP and DNS. Suddenly hostnames were domain names. But it was also convenient not to have to fully qualify every name, every time, hence there are fully qualified hostnames and unqualified hostnames In Unix land, hostnames and domain names are still used interchangeably. (Microsoft tends to butcher existing technical venacular for its own ends -- things could be different there.) It helps that most computers have only one network card, so only one IP address, so only one domain name. But even when that's not true, when a computer has more than one nic it's said to be multi-homed, we still say the computer as has multiple hostnames.
Even when you are talking about what goes on on the IP based network behind the NAT firewall or server farm load-sharing device, you're talking about a more-or-less isolated Internet that can and usually does have it's own DNS namespace and the domains in that namespace are hostnames on that network. Usually there's effectively one level in that hidden namespace, but not for larger organizations.
Incidently, there are other sorts of names in DNS besides hostnames, so the hostname term also serves to distinguish those DNS names that are asscoiated with computers from those that arn't. All of them are, technically, domain names, whether or not they are associated with a computer. (Or more precisely, with a network port.) --kop 07:55, 18 June 2006 (UTC)[reply]
BTW, you should definately take a look at domain name. I've reworked it and lots of related stuff like domain, subdomain, top-level domain, Domain Name System, DNS, and zone. --kop 08:19, 18 June 2006 (UTC)[reply]