Here are the pcaps from the server in question.
ftp://ftp.sonic.net/pub/users/gkeller/tcp_pcap
Thank you for your help so far.
Hello Grant,
On Sep 30, 2011, at 7:12 PM, Grant Keller wrote:
We have been having this problem with TCP queries timing out on one of our
nameservers running pdns 3. We have a monitor that runs every two minutes, and
every half hour or so it times out on its query. I can reproduce this by
running the following:
while [ 1 ]; do
dig schwer.us +recurse +tcp +short +time=1 +retry=1 @c.ns.sr.sonic.net
date
sleep 1
done
If I let that run for a while, it will capture several timeouts:
;<<>> DiG 9.7.3<<>> schwer.us +recurse +tcp +short +time=1 +retry=1
@c.ns.sr.sonic.net
;; global options: +cmd
;; connection timed out; no servers could be reached
The pdns.log has no significant entries at the times that this occures. I have
watched iptraf as I recieve the timeouts, and It dosn't seem that we are
hitting our max number of tcp connections (1000). This problem first started in
pdns-2.9.22, and continued after the upgrade. None of our other name servers
have this problem.
What would be the next step in troubleshooting this? Are there any extra
logging options I can turn on? Thanks in advance.
Most important to know, of course, is whether the queries even reach pdns. Are
you in a position to run tcpdump/tshark on c.ns.sr.sonic.net, to monitor
requests from a test run like the one described above?
Kind regards,
Peter van Dijk
--
Grant Keller
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