(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 (188.8.131.52) via Comcast Internet connectivity;
- My employer’s internal caching DNS;
- Google (184.108.40.206) via my employer’s Internet connectivity (mostly Level 3);
- Google (220.127.116.11) via Comcast; and
- Google (18.104.22.168) 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.
Read the rest of this entry »