net Gateways and other administrative hosts for a network (it does not mean all of the hosts in a network). {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 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.
FQDN (Fully Qualified Domain Name)
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.
Internet Numbers
Every single machine on the Internet has a unique address, {At least one address, possibly two or even three—-but we won't go into that.} called its Internet number or IP Address. It's actually a 32-bit number, but is most commonly represented as four numbers joined by periods (.), like 147.31.254.130. This is sometimes also called a dotted quad; there are literally thousands of different possible dotted quads. The ARPAnet (the mother to today's Internet) originally only had the capacity to have up to 256 systems on it because of the way each system was addressed. In the early eighties, it became clear that things would fast outgrow such a small limit; the 32-bit addressing method was born, freeing thousands of host numbers.
Each piece of an Internet address (like 192) is called an "octet," representing one of four sets of eight bits. The first two or three pieces (e.g. 192.55.239) represent the network that a system is on, called its subnet. For example, all of the computers for Wesleyan University are in the subnet 129.133. They can have numbers like 129.133.10.10, 129.133.230.19, up to 65 thousand possible combinations (possible computers).
IP addresses and domain names aren't assigned arbitrarily—-that would lead to unbelievable confusion. An application must be filed with the Network Information Center (NIC), either electronically (to hostmaster@nic.ddn.mil) or via regular mail.