[Pdns-users] Occasional TCP query timeouts.

Grant Keller gkeller at corp.sonic.net
Fri Sep 30 17:12:28 UTC 2011


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
sleep 1

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 
;; 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.

Grant Keller

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