How to find my DNS Server address in Windows 7
You want to open "Run" then type
cmd.exe
In the command prompt enter this command
C:\>ipconfig /all | findstr /R "DNS\ Servers"
The output should look something like:
If you know your public IP address simply enter in a command prompt window:
nslookup <your public IP>
You can also specify the name server to check against by appending it to the above command.
You can get your current IP address from sites like http://whatismyip.com
Personally, I prefer this approach:
echo | nslookup | findstr "Default\ Server"
It will print the name of your default DNS server in the shell