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Domains

invisible.xbm

Getting where you want to go can often be one of the more difficult aspects of using networks. The variety of ways that places are named will probably leave a blank stare on your face at first. Don't fret; there is a method to this apparent madness.

If someone were to ask for a home address, they would probably expect a street, apartment, city, state, and zip code. That's all the information the post office needs to deliver mail in a reasonably speedy fashion. Likewise, computer addresses have a structure to them. The general form is:

a person's email address on a computer: user@somewhere.domain
a computer's name: somewhere.domain

The user portion is usually the person's account name on the system, though it doesn't have to be. somewhere.domain tells you the name of a system or location, and what kind of organization it is. The trailing domain is often one of the following:

com
Usually a company or other commercial institution or organization, like Convex Computers (`convex.com').

edu
An educational institution, e.g. New York University, named `nyu.edu'.

gov
A government site; for example, NASA is `nasa.gov'.

mil
A military site, like the Air Force (`af.mil').

net
Gateways and other administrative hosts for a network (it does not mean all of the hosts in a network).(1) One such gateway is `near.net'.

org
invisible.xbm This is a domain reserved for private organizations, who don't comfortably fit in the other classes of domains. One example is the Electronic Frontier Foundation (see section The Electronic Frontier Foundation), named `eff.org'.

Each country also has its own top-level domain. For example, the us domain includes each of the fifty states. Other countries represented with domains include:

au
Australia
ca
Canada
fr
France
uk
The United Kingdom. These also have sub-domains of things like `ac.uk' for academic sites and `co.uk' for commercial ones.

invisible.xbm The proper terminology for a site's domain name (somewhere.domain above) is its Fully Qualified Domain Name (FQDN). It is usually selected to give a clear indication of the site's organization or sponsoring agent. For example, the Massachusetts Institute of Technology's FQDN is `mit.edu'; similarly, Apple Computer's domain name is `apple.com'. While such obvious names are usually the norm, there are the occasional exceptions that are ambiguous enough to mislead--like `vt.edu', which on first impulse one might surmise is an educational institution of some sort in Vermont; not so. It's actually the domain name for Virginia Tech. In most cases it's relatively easy to glean the meaning of a domain name--such confusion is far from the norm.

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