The DNS Timing Report will test to see how long it takes for your DNS servers to respond, taking many factors into consideration (timeouts, lame delegations, etc.), and gives you a score (from an F to an A+). It then lists any problems (such as a slow response, timeouts, etc.). Normally, you would enter www.example.com and use the A record (you can use other hosts or records, but the timing is typically the same). This test can be useful in comparing two different web hosts that provide DNS service.