(Approx. 911 words)

Internet Addressing

by Hilton Kaufman, a Member of the Chicago Computer Society

www.ccs.org

hmkaufman(at)earthlink.net

(This is the third article in a series explaining the Internet. The previous articles provided a general overview and explained how the system is hooked together.)

Obtained from APCUG with the author's permission for publication by APCUG member groups.

Each individual or computer on the Internet has an individual and unique address in the system. Part of this address might reflect how messages to and from this address are routed, but it is possible to buy or rent what is known as a domain name. Within the system, everything is routed by numbers, but there are tables available to many servers that translate the easier for mere humans to understand names to the proper routing numbers.

There is a regular hierarchy to how these names work and are assigned. Generally if you control a domain name, you can control the individual names under it. There are individuals who only use one individual name under a domain name. This might be done to advertise a company or service. An ISP might have thousands of names under its domain.

An international agency, called ICANN, that is subject to control by the U.S. Department of Commerce if it gets out of line, assigns the high level domains, such as .com. There are between 100 and 150 of these high level domain names. An authority for each of these high level names registers the specific domain names. Every nation-state has its own high level name, such as .de for Germany (Deutschland). Some are general or for certain types of users, such as .com and .edu.

ICANN also arranges for several high level servers in different locations to have the master list for the system. I believe that there are currently seven of these servers. If one is lost or compromised, the others can still function and quickly correct the data on the other ones. Much of this information is also fed down the line to other name translation servers on a regular basis.

The rules as to how a domain will be issued under a specific high level varies with the issuing authority. They may contract the administration out to a service, such as VeriSign, that does this for a profit. Sometimes the rules are strict and might require an actual presence, type of entity and/or citizenship to use a domain name with a particular national high level name. In other cases, it may simply be whether or not one is willing to pay the required fee. The small pacific island nation of Tuvalu covers much of its government expenses by selling .tv domain names through VeriSign. Tuvalu is not even mentioned in the online advertisement for .tv domain names.

Specific names work a bit different for e-mail than for the World Wide Web. Typically an individual will have an e-mail address, but not a uniform resource locator (URL) for the Web. The e-mail format is a bit easier to explain, so I’ll start with it.

In an e-mail address, the individual name is to the left of an at “@” symbol, which separates the two parts of the name. Immediately after the @, the specific part of the domain name follows. A dot, or period, separates this from the high level domain name. An example might be something like Joe.Individual@example.com. There may or may not be dots and capitals in the individual part of the name. There is always at least one dot in the domain name.

The individual web site services that go through the consumer ISPs as a free feature are a bit weird looking. Any business would probably have and use its own domain name. With web sites the domain name comes first, followed by a slash and then the individual part of the name. You can control the specific page naming from whatever level you are able to work. It will probably not have names of individuals. It may or may not start with www. If it is directly at the domain name level, it might default to a specific page name, such as index. A technical requirement of the web sort of requires that http:// appear before the actual URL. The frequently seen www is not required. Letters such as httm or htm, to indicate how the site is coded, are at the end. An example might be http://example.com/index.htm. ■

(The remaining two articles explore services available over the Internet. The first will cover e-mail and the World Wide Web. The second lists many of the less known services that are available to those who might be interested.)

Hilton Kaufman serves as the technical support person for the procedures writing unit of an Illinois state agency, where higher level technical support personnel are concerned with the details of Internet connections and services. As such, he uses the software provided to him to create forms, convert documents into PDFs, advise members of his unit as to how to use the available software, and similar tasks. For his home computer, he can go all out and get a powerful machine that allows him to do things like playing games and surf the web without getting in trouble. He has prepared a number of articles aimed at novice users on the basics of standard computer programs.

This article has been provided to APCUG by the author solely for publication by APCUG member groups. All other uses require the permission of the author (see e-mail address above).