Internet Addresses

The Naming System

TCP/IP Protocols | Packets of Information | Addresses | The Naming System | Finding Addresses | Going Futher

Let us consider as a typical example the internet address

www.techcorps.org

which is actually the name of the IP address 160.36.28.57. How did the people who run the Internet come up with that name, and how did we know that www.techcorps.org is really a nickname for 160.36.28.57?

The symbolic name of a site is determined by a naming standard known as the Domain Name System or DNS. Each field in a symbolic address corresponds to a single domain. The first field is a host name, which identifies a single computer. The last field is a top level domain. In between are things like department names, organization names, and so on in order of increasing generality.

For example, www.techcorps.org is the address for the main server of Tech Corps, which explains the ".techcorps" in the name, and this is an organization, which explains the ".org" part of the name. When we want to be precise we will term a sequence like 160.36.28.37 an IP address, while we will call the corresponding name csep10.phys.utk.edu the DNS name for the computer with IP address 160.36.28.37. However, in many instances we will use the term "IP address" to refer loosely to either the number or the name.

Some top level domains in the US and some sample addresses are listed in the preceding figure. Addresses of sites outside the US end with a two-letter country code; some common country codes are also listed in this figure.