recursive-clients queue size & clean-up

[Steinar Haug]

[Ladislav Vobr]

|   Does each slot in the recursive-client queue being clean up after the 
|   timeout expire, if there is no response?  Or some slots are being 
|   occupied longer, it seems to me that when I reach this limit there is no 
|   really way back to stabilize bind, all cpu will be used and even if I 
|   leave it over night when the traffic sometimes goes as little as 300-400 
|   req/sec it will not recover and still the messages keeps coming from 
|   time to time, cpu is very high (abnormal to the number of incoming 
|   requests) and number of requests logged to the query.log file is almost 
|   just half of what the box is really suppose to receive, (looks like bind 
|   or os dropping the traffic).
|   There is no weird traffic, maybe there was a weird spike, but it should 
|   recover. When I stop and start  service resumes, cpu drops, traffic 
|   comes back to normal rate, not almost like half rate as it was during 
|   the problem, and recursive-client queue is not overflowed.

We have seen similar problems. Our current conclusion is that BIND9 is
not very good as a recursive name server, and that it probably has bugs
involving large cache sizes and/or high query rates. We are currently
evaluating Nominum CNS, which so far seems to perform *much* better.
Nominum CNS is not free, of course...

Steinar Haug, Nethelp consulting, sthaug at nethelp.no