Domain Names and Addresses

Each node on the Internet has a numeric address called its IP address. Additionally most sites also have a name called the fully qualified domain name.
These names are usually 3 or 4 strings separated by dots (periods). The names are associated with numerical IP (Internet Protocol) addresses

        Domain Name                     IP Address          

These domain names are used as part of an e-mail address and also used to access Internet services and resources.

To send electronic mail to someone you need to know their Internet address.
For nodes that are directly connected to the Internet this address is usually login-name@domain-name

To access an Internet service or resource you usually start a program, for example, a Web browser such as Netscape Navigator, and give the address of a remote site or service that will interact with the program you start.

Access to Internet services and resources is specified as a URL or Uniform Resource Locator. Two examples are

Be careful that the names you type are correct in terms of upper or lower case of letters, spelling, and punctuation.

The most general form of a URL is


Many of the services and resources available on the Internet operate according to a client-server model. You run a program on your computer to access information on a remote system. The program on your computer, such as a Web browser acts as a client, accepting your input and then passing it on to the other system which is running a program that acts as a server. That is, it accepts requests form clients, acts on the request, and then send a