The Domain Name System (DNS) is essentially the telephone book of the Internet. This service is what guides your computer to a website when you type the address--www.eHow.com, for instance--into your Internet browser. If you did not have a DNS server directing your Internet, you would have to manually enter the IP address of every website you wanted to visit. DNS servers, like all servers on the Internet, have a fixed IP address as well, and finding that address is quite simple.
Click the Start menu and select "Run."
Type "cmd" into the text box that appears and press "Enter."
Type "cd/" into the command prompt window that appears, then press "Enter."
Type "C:>ipconfig /all" and press "Enter." This will present a screen full of information, including the primary and secondary DNS server addresses down near the bottom, which look like a series of numbers separated by dots as in 192.168.1.2, for example.