From Marx Bitware:
This handy little tool queries two DNS servers and lists the IP addresses returned. If you are having connection problems, or are being directed to the wrong site, then a corrupt DNS server can be the cause. You are free to enter the IP address of any DNS server and analyze the returned results. The program works by obtaining random website addresses from Google. These addresses are then sent to each of the DNS servers and the results of the lookups are displayed by the application. The program is set to query two major DNS servers by default, however, any valid DNS server will work.