Advocates of anycast dns services claim that anycast dns is inherently faster than unicast dns. These claims are often made as self-evident fact without further substantiation.
However, it is possible to test this claim using publically available tools from independent sources.
just-dnslookup.com is a site that times dns lookups from 59 globally dispersed data centers as of the time of this test.
intodns.com was used to verify the published authoritative name servers for each domain.
The tests were performed for a domain using anycast dns and a domain using unicast dns. The results show that not only is unicast competitive with anycast, it is often faster. The claim that anycast is inherently faster than unicast is simply not viable in the light of these test results.
COMBINED TEST RESULT, 2011-07-27
The composite screenshot to the right shows the dns query times from both anycast and unicast lookups for two A records.
It has been created by combining parts of the two screenshots in the following sections.
This has been created solely for ease of viewing on a single page.
The composite data remains the same as the source data.
The icon colors appear to have the following meanings:
click thumbnail images to view full size
ANYCAST TEST RESULT, 2011-07-27 06:10 GMT (dnsmadeeasy)
UNICAST TEST RESULT, 2011-07-27 06:18 GMT (edgedirector)