[f-nsp] DNS servers behind ServerIRON XL

[Paul Raj Khangure]

On Sun, Jan 20, 2008 at 12:11:27PM -0500, Drew Weaver wrote:
> 
> I am curious if anyone has ever ran into an issue where they are using
> a ServerIRON XL to load balance DNS servers but for some reason one of
> the DNS servers out of X has an exponentially higher number of
> connections in show server real <servername> than the other real
> servers. This behavior is also indicated by the fact that the CPU load
> on that specific server is at 99% and the others are at 11 or so
> percent.. I also note that it is ALWAYS the first server in the list
> which is the exponentially more used server.

Which DNS software (and version) are you using?

I've seen a problem with BIND 9.2 where when it starts expiring data
from the cache, the performance of the box drops significantly, and it
can end up with more connections that it can handle.

Supposedly this was fixed in BIND 9.4.

You might want to try least connections instead of round robin, if all
your boxes are of similar spec. Add weighting if you need to favour a
lower specc'ed box.

Good luck,

prk.