Test Driving Google Public DNS (Updated with OpenDNS comparison)
Google announced its Public DNS service this morning, claiming enhanced performance and security; I took it for a brief test drive with the following results.
(See bottom of post for an update running similar tests on OpenDNS.)
Methods: I searched Google for keywords that I believed fell somewhere between obscure and common and collected the first ten hostnames printed on the screen. I then used local installations of dig to query a collection of DNS servers for the hostnames’ A records and collected the response times. The different resolvers used were:
- A local BIND installation (127.0.0.1, cache empty) with Comcast Internet connectivity;
- A Comcast DNS server (22.214.171.124) via Comcast Internet connectivity;
- My employer’s internal caching DNS;
- Google (126.96.36.199) via my employer’s Internet connectivity (mostly Level 3);
- Google (188.8.131.52) via Comcast; and
- Google (184.108.40.206) via an Amazon EC2 instance in us-east-1a.
Anticipating a bimodal distribution of results, I assumed high latency responses were cache misses, while low latency responses were cache hits, and categorized results correspondingly.