"The problem with DNS servers is that they are heavily used, and a heavily used server will be slower than a server with little load. Your ISP probably sets an optimal DNS for you, but not always. Also, if you are behind a rounter or NAT, it’s likely that it is acting as your DNS. Especially if you are at home behind a router, consumer level router products are pretty poor at handling DNS optimally. Either way, it is a good idea to find what is the best DNS for you!
"There are two very popular methods. Both methods work, but one is preferred. There is the NameBench program on Google Code and the GRC program DNS Benchmark (which is the preferred product). Both are free and great, but I trust GRC greatly. Both are free, but only NameBench is open source.
"Note though, that both program will take a while to execute. They need this time to test all their known servers and then some. So give it some time. Grab some tea and munchies, might be a while."
