Recent problems with Reverse DNS.

Three weeks ago our internal clients were able to connect to hosts by ip
address quickly. Then we started noticing slow connection to various internal
host by IP address. If I add a host entry of my workstation to the server I'm
connecting to then things are fast again. Sounds like a Reverse DNS problem.
So I updated our db.cache file (which contains the root servers) on both DNS
server and things seemed to be fast again after restarting Bind. But then 10
minutes later things slowed down again.
Our hosts that have public IPs with FQDN are fine. Just the internal hosts
have problems.

Brett