Choosing fast DNS servers will speed up your web browsing experience. Usually it’s the best to use the DNS servers that your ISP provides as they are physically closest. But that’s not always the case and you can easily test it with a free opensource DNS benchmark utility called Namebench.
Nambench is available for Linux, OS X and Windows and can also be installed via the Ubuntu Software Center. After Namebench runs a series of tests the results are displayed in your web browser and look something like this:
Help on how to interpret the results and how to pick the fastest servers can be found at http://code.google.com/p/namebench/wiki/FAQ
And here a list of some free DNS servers that usually work well.
Google DNS server:
OpenDNS DNS server:
Level3 DNS server:
18.104.22.168 (probably the most famous dns server before 22.214.171.124 was born)
Additional Note: In Linux and OS X you can also use the dig command to test a DNS server, e.g. to check how fast the Google DNS server resolves this site:
dig www.sysadminworld.com @126.96.36.199