BIND occassional slowdowns
daniel.ryslink at col.cz
Mon Jun 5 14:55:50 UTC 2006
I have run into a problem with one of our caching DNS resolvers running
currently BIND 9.3.2 on FreeBSD 4.11. The problem manifests itself as
occassional slowdown in response from the average 1-3 ms to sometimess well
over 3000ms. The anomaly always lasts only a few seconds, and after that the
normal operation resumes.
Though the DNS responses are never lost, such a delay usually causes
timeouts on our mailservers that use this machine for resolving, usually
resulting in delayed mail, application timouts and other unpleasant
I believe that the hardware is sufficient, because the named process mostly
takes 7-10% of the CPU and about 450MB (out of 1G) of available RAM. The
server usually has about 300 simultaneous caching queries at one time. I
also checked the various OS limits like maxprocs, max open files,
nmbclusters, bandwidth usage, and the machine does not seem to be lacking
The nameserver serves both as authoritative and caching nameserver (I know
it's not recommended, and we are working on moving all the zones away to
make it purely caching resolver).
If anyone experienced similar problems, all advices are most welcome.
Thank you in advance.
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