I've been having some intermittent dns problems with a web server, where certain isp's dns servers don't have my hostnames in cache and fail to look them up. At the same time, queries to opendns for those hostnames resolve correctly. It's intermittent, and it always works fine for me, so it's hard to identify the problem when someone reports connectivity problems to my site.

In trying to figure this out, I've been looking at my logs to see if there are any errors I should know about.

I found thousands of the following messages in my logs, from different ip's, but all requesting similar dns records:

May 12 11:42:13 localhost named[26399]: client 94.76.107.2#36141: query (cache) 'burningpianos.com/MX/IN' denied
May 12 11:42:13 localhost named[26399]: client 94.76.107.2#29075: query (cache) 'burningpianos.com/MX/IN' denied
May 12 11:42:13 localhost named[26399]: client 94.76.107.2#47924: query (cache) 'burningpianos.com/MX/IN' denied
May 12 11:42:13 localhost named[26399]: client 94.76.107.2#4727: query (cache) 'burningpianos.com/MX/IN' denied
May 12 11:42:14 localhost named[26399]: client 94.76.107.2#16153: query (cache) 'burningpianos.com/MX/IN' denied
May 12 11:42:14 localhost named[26399]: client 94.76.107.2#40267: query (cache) 'burningpianos.com/MX/IN' denied
May 12 11:43:35 localhost named[26399]: client 82.209.240.241#63507: query (cache) 'burningpianos.com/MX/IN' denied
May 12 11:43:35 localhost named[26399]: client 82.209.240.241#63721: query (cache) 'burningpianos.org/MX/IN' denied
May 12 11:43:36 localhost named[26399]: client 82.209.240.241#3537: query (cache) 'burningpianos.com/MX/IN' denied

I've read of Dan Kaminski's dns cache poisoning vulnerability, and I'm wondering if these log records are an attempt by some evildoer to attack my dns server.

There are thousands of records in my logs, all requesting "burningpianos", some for com and some for org, most looking for an mx record. There are requests from multiple ip's, but each ip will request hundreds of times per day.

So this smells to me like an attack. What is the defense against this?