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
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). (Footnote: The Matrix 111) One such gateway is 'near.net'.
org
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 8.3.3 [EFF], page 66), 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
Pk
Pakistan
uk
The United Kingdom. These also have sub-domains of things like 'ac.uk' for academic sites and 'co.uk' for commercial ones.
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 ob- vious 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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