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."
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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.