In the spirit of testing things before concluding anything, I decided to test Google’s new Public DNS service against OpenDNS, 4.2.2.2 (a DNS server owned by Level 3), and the DNS servers on my network.
To test the service, I modified the excellent script created by Manu J.
#!/bin/sh cur_dns=`cat /etc/resolv.conf | grep "nameserver" | tr -cs '0-9.' '[\n*]'` for i in "lifehacker.com" "facebook.com" "manu-j.com" "reddit.com" "tb4.fr" "bbc.co.uk" "intmain.net" do for j in "4.2.2.2" "8.8.8.8" "208.67.222.222" $cur_dns do echo "\n$i\n$j" for k in $(seq 1 100) do echo `dig @$j $i | grep Query | awk -F ':' '{print $2}' | tr -cs '0-9' '[\n*]'` done done done
My two changes were to grab the DNS servers defined in /etc/resolv.conf and to query each service 100 times. Of course, the only downside to this test is that it does not account for the DNS server caching the result of repeated queries. This effect shows up in a few of the graphs (included below).
Google’s DNS service is very consistent in speed, but is also consistently slower than any of the other servers tested. Google’s DNS service also shows very little difference with repeated requests, except for the lookup of intmain.net, where the first request took significantly longer than the others. Similarly, Google’s DNS took over 2 seconds to respond to a request of reddit.com. The final ordering is as such: the fastest in most cases was the DNS servers local to the network (except for uncommon sites, which took between 100ms and 150ms for the first request), followed by 4.2.2.2, followed by OpenDNS, and trailed by Google Public DNS.
I encourage you to perform the same (or similar) tests on your own computers and share the results. It’s very hard to tell if the differences in response times are caused by latency or lookup time, but it is clear that the best DNS servers for me to use are the ones local to my network at UCLA.
