Namebench is an open source DNS test service. Spawned from the new Google DNS service. 

DNS is a major part of how the internet works.  Simply put, it resolves names to the actual numbered address for a webpage. Every webpage has a unique number.  We use names and letters in our address bar for simplicity.  However, the web actually moves around via numbers.  Google is www.google.com.  But it’s real address is 64.233.181.147. 

  Your ISP automatically provides a DNS name server with your connection.  However, it is not always the fastest or safest.  You can change setting in your router or modem  of even on your PC to use a different DNS.  A faster DNS means webpage's load faster.  Also, other DNS services can be safer as they warn you about potential Phishing sites or other problems.  Open DNS allows for configuration based on a free account.  You can block websites or keywords via DNS.

  Namebench is a small application you download and run on your PC.  It takes about ten minutes to complete.  It will they give you results for the best DNS choices based on your location.  DNS is location specific, so one DNS may be better in one area and worse in another.  You can only really one this application once from your PC.  Since running it multiple times messes with the DNS resolves and will produce false results.

  I still prefer Open DNS ( Open DNS ) and the free version they provide.  I also prefer to change the DNS setting in my router rather than run the tray application they provide.