While it is possible for Internet clients to access a server by using its IP address, remembering a long number for each of your favorite sites can be difficult, if not impossible. That’s why Domain Name Service (DNS) is so useful. Domain Name Service is in the business of broadcasting more "friendly" names across the Internet, which point to corresponding IP addresses. With DNS, anyone can simply type in a domain name, which gets resolved, or translated, to the numeric IP address of a computer. With some Web browsers, for example, you can see a domain resolution happen in the status bar at the bottom of the browser window. When you type in a Web address, such as http://www.cnn.com/, the status bar of your browser may say:
Connecting to site 207.25.71.5...
Web site found, waiting for reply...
Your computer was able to match the IP address of the CNN's machine, which is 207.25.71.5, to the domain name you entered. In order to do this, your computer needed to have some sort of reference, where it could look up domain names and match them to their corresponding IP addresses – in the same manner that you would use a phone book to look up someone’s name to get their telephone number. The Internet’s version of this "electronic phone book" is called a Domain Name Server, and is commonly referred to as simply a Name Server. When you initially set up your computer to connect to the Internet, you were required to give it at least one name server so it would know where to look up the IP addresses of the domain names you access. Most people use two name servers, called primary and secondary name servers, so that there is a backup in the event of a failure. In the above example, you could have simply typed in the IP address of the server and the connection would have been made without needing to consult a name server. However, most people on the Internet rely heavily on DNS, so that they don’t have to worry about keeping track of all those IP addresses.
A name server’s only function is to maintain a table of domain names and matching IP addresses, called a DNS Table. Each domain name on the Internet has specific DNS servers that are responsible for keeping their information in their table, and that DNS server is then responsible for broadcasting that information across the Internet. Most likely, you chose a domain name for your NT account when you first signed up. Your domain already has an entry in the DNS tables of our name servers, and this entry is an important part of what makes it possible for people to access your virtual account on the Internet.