My internet provider’s DNS servers are slow. At least, this is what I had come to believe when I set out in search of better ones. Aside from the fact that fast, reliable, public nameservers are scarce, I came away with more questions than I went in with.
I run a small network in my apartment building using a D-Link 802.11g router which lets me set nameservers that override any defaults that might otherwise have been garnered from my internet provider. My wish was to find a pair of addresses that I could query for once and for all and use them as my default servers at the router level.
A search for “public+name+servers” uncovers OpenNIC’s Public Name Servers but their site confuses me, especially when I read directly above a list of server addresses that,
...users may not query these servers directly, as they are intended for terminating recursive queries by the user’s nearest Tier 2 server.
If users aren’t permitted to query them, why are they listed on the public dns server page? What happens if I do use them—will I get in trouble? Further down in the page, there is a list of Tier 2 servers but there are none geographically close to me. Still, I tested them anyway and concluded that they were slower than my providers.
Frustrated, I had the sudden idea of using http://dnsstuff.com’s ISP Cached DNS Lookup to see which elite dns servers were considered ‘popular’ enough to have made the shortlist. The example above (google.com) produces acceptable results – most servers queried have this popular domain name cached and don’t need to look it up. The query times are also reasonable – if you look closely, you can start to see a pattern emerge. Some servers are ‘faster’ than others. Factor in the cache time too—the shorter it is, the more likely your queries are to be accurate.
In the google.com race, 14 of the 51 servers have a cached answer. Unless I’m horribly mistaken, this is a good thing. Why bother the root servers for such a common query with an ip address that’s quite unlikely to change?
Consider this query of backpackit.com. As of the time of this writing, only one server has this domain cached.
I began querying additional domains with increasing obscurity to observe the cache to popularity ratio and found interesting results. Mainstream domains, such as google.com, hotmail.com, and cnn.com are nearly always cached followed by domains like slashdot.org, which are cached by about half of the servers. Less popular domains like flickr.com, and del.icio.us are cached in only about one quarter of the instances, and finally domains like shiftmedia.net or even backpackit.com are not cached at all.
The list of knowledgeble servers whittled away as I offered more and more contenders – ibm.com, sun.com, textdrive.com, mozilla.org, debian.org, and my final query—rubyonrails.org – left only two servers remaining: SpryNet and UUNet, whom I pronouce the hippest domain name servers ever, for now.
