Adventures in Caching DNS
I had been using a number of feeder servers in my caching domain name server configuration. It seems that I have also been firewalling a number of spammers on some of those networks providing the servers.
This resulted in failure of the feed (though none of the subnets upon which the feeding servers themselves reside were in the mix) and so I had to drop back and punt.
After a hasty reconfiguration of the caching DNS on my cluster things seem to be calming down.
The moral of the story is to use a caching DNS feeder server on networks outside those spammer realms you attempt to firewall.
Meh.