[Unbound-users] Unbound stops resolving some hosts sporadically
lists at cloned.org.uk
Tue Mar 29 10:46:17 UTC 2011
I'm running unbound 1.4.6-1 from debian squeeze on a couple of machines as
a resolver and have come across strange problems where unbound will stop
resolving some hosts. It seems sporadic as to what works and what doesn't,
but nagios generally reports that it timed out after 10s when trying to
resolve www.google.com. I sometimes notice it before nagios does if using
that resolver. I've tried sniffing traffic but it's hard to pinpoint
queries as the servers are quite busy.
What I've noticed though is that sometimes for example i won't be able to
resolve yahoo.com but after a minute or two it works again, but then fails
a few mins after that. I don't believe there is a network problem as it
fails for some domains whilst working for others which are on the same
name servers. others on the same.
If I restart unbound it clears up the problem, but this is obviously less
than ideal. I'm tending to do this once a day now, sometimes more
frequently. I've moved one of the resolvers over to other software now to
try and avoid issues where they are both broken for obvious reasons.
Server config looks like this from the one which is still being used
(minus interface, outgoing-interface and access-control lines):
The other I tweaked slightly with socket receive buffers in case it was
using all sockets but it didn't make any difference:
# cat /proc/sys/net/core/rmem_max
Logs didn't really show much, and produce too much data to trawl through
This morning I've changed to running one thread and when I receive a
problem just now dumped stats which were as follows:
# unbound-control status
modules: 2 [ validator iterator ]
uptime: 3095 seconds
unbound (pid 24730) is running...
# unbound-control stats_noreset
I've read the changelogs of newer versions but can't see anything that
looks like this problem. I'd prefer to avoid upgrading to the latest
source distribution on the off-chance it will fix it as that just seems
like clutching at straws.
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