Internet Addresses

E-mail addresses are comprised of two sections: user name and IP address. The user name is given to the user by a system administrator who is running the network that the user is accessing the internet through. IP addresses are made up of four numbers which are each less than 256. For instance, an email address which uses an IP address would look something like this: jknight@196.92.108.7 (the @ separates the user name, jknight, from the address). Pretty easy to remember, huh?

To simplify things a bit, it is now more common to use Domain Names, developed in 1983 at the University of Wisconsin, which represent the IP addresses. For instance, to send an email to someone at the University of Nevada, Reno, you would send an email with the domain name address of unr.edu which would look like this:

jknight@unr.edu

Much better than remembering strings of numbers!

For those of you who still may be confused, the domain name addresses are codes which can be broken. For instance, unr.edu means that you are accessing a user named jknight who uses the computer network at the University of Nevada, Reno (unr), which is an educational institution (edu). Sometimes you may run across domain name addresses which are much longer such as:

jknight@equinox.unr.edu

Domain names get more specific, moving from right to left. So the above address is saying that you are emailing jknight who is a user of a computer known as equinox at the University of Nevada, Reno (unr), which is an educational institution (edu). People who subscribe to services such as America Online will have e-mail addresses with domain names such as jknight@aol.com, which means that they are users of America Online (aol), a commercial provider (com).

The final part of the domain name is called the High-Level Domain. In addition to edu and com, other common high-level domains in the United States include: gov (government), mil (military), net (usually found in state-run networks) and org (organizations). International e-mail addresses sometimes have other high-level domains, such as their country name. For example, Iceland uses the high-level domain extension of .is so they might have an address that reads:

jknight@uis.edu.is

As you will see in later sections, domain name addresses are also used in addresses for the World Wide Web, Gopher and FTP.