Ultra-slow DB connection / Reverse DNS

Our network admin did some work with load balancing on our test system last night. This morning, I came in and tried to SSH into our fileserver, and it took forever. Ditto for SSHing within the network. Ditto for any MySQL connection, including the connections that the app servers make.

I'm sure this is due to Reverse DNS lookup attempts. When I added host entries for all the machines that connect (including the public IP of the network I'm on), everything went back to normal.

What I don't understand is why this would happen overnight. The network guy only made changes on how the system connects to the public internet, so the internal network supposedly didn't change at all. Why, then, am I having all these problems within the network?

I know that this may not be the most appropriate place for such a question, but I know that there are a lot of knowledgeable people on this group, and I'm guessing this may have happened to someone else. Any ideas would be welcome.


Apparently, outgoing NAT was disabled on the load balancer's configuration by default. The only thing I can think of is that the servers were trying for a reverse DNS lookup, never got a responce back, and had to wait until they timed out before letting anyone in.

Jason Norris wrote: