DNS fun

Diagnosing DNS trouble is especially fun because of caching. If you keep doing dig over and over, all you’re usually doing is reading the cached value from your local DNS server, rather than confirming that the changes you’ve made at your registrar are taking effect. So I came up with the following method to try to trace exactly what was happening. It might be wrong, but it seems to make sense.

  1. dig The hope in doing this was that I’d get an NXDOMAIN error from the highest possible authority (i.e., farthest from my local DNS). This returned the following:


    com. 10800 IN SOA 1120164931 1800 900 604800 900

  2. dig In other words, ask what it thinks about


    . 172800 IN NS . 172800 IN NS

  3. dig Lather, rinse, repeat:


    org. 172800 IN NS

  4. dig Ah, now we’re getting somewhere:

 86400 IN NS 86400 IN NS

At this point I figured out that the root nameservers had the wrong nameservers listed for my domain. So I continued to fiddle with the registrar’s self-service web page, and eventually got it right.