Maintained by: NLnet Labs

[Unbound-users] No answers from unbound occasionally

Attila Nagy
Thu Jun 4 14:41:58 CEST 2009


W.C.A. Wijngaards wrote:
>> I don't know how long unbound waits for an answer, but I see about 10-30
>> lines per second per server from this. Do you think it's normal? (there
>> are about 4k qps currently)
> Well, unbound normally sets its smoothed roundtrip time timeout that it
> calculated as the time out, and when that timer expires, it closes the
> socket.  It can then re-use the socket to open another (random) port to
> send the next query on.  This next query could well be the retry for the
> just failed one, with exponential backoff on the timer.
I've made a capture and according to that, it was about 150 ms between 
unbound's query and the response. I think it's pretty normal for 
nameservers on the other side of the globe.
> So, it is normal that some authority servers are slow.  Thus produce
> timeouts.  20 / 4000 is 0.5% of cases for you, this looks very
> reasonable to me.
Yes, maybe, my problem is that I can see unanswered queries. If I 
understand it correctly, the above situation should not result in a loss 
of answer towards the resolver client.

And this is my primary concern, because I don't understand why those 
queries are left unanswered.