Determine the exact performance of local and remote DNS nameservers.
GRC's DNS Benchmark performs a detailed analysis and comparison of the operational performance and reliability of any set of up to 200 DNS nameservers (sometimes also called resolvers) at once. When the Benchmark is started in its default configuration, it identifies all DNS nameservers the user's system is currently configured to use and adds them to its built-in list of publicly available "alternative" nameservers. Each DNS nameserver in the benchmark list is carefully "characterized" to determine its suitability -- to you -- for your use as a DNS resolver. This characterization includes testing each nameserver for its "redirection" behavior: whether it returns an error for a bad domain request, or redirects a user's web browser to a commercial marketing-oriented page. While such behavior may be acceptable to some users, others may find this objectionable.
Response times change during the day. So you can identify the top 3 DNS on one scan, but a scan only a few minutes later identifies one different DNS or tells you the order in which you've designated your DNS is incorrect. It issues a message that "X number of servers are ABSOLUTELY faster than" the ones you've set. It's the "ABSOLUTELY" that's the problem. Because response times change minute by minute, no one can say any you've chosen as your defaults are ABSOLUTELY slower than X number of others.
Summary
Is probably the best program on the Web for determining DNS response times. But it needs to back off on the claim after every run that some server you selected as one of your defaults is "absolutely" slower than X others. It shouldn't say that, because Internet activity can alter response times based on the time you ran the program.