[Pdns-users] Possible tcp listener issue

Simon Bedford sbedford at plus.net
Thu Mar 25 15:51:29 UTC 2010


We have upgraded our customer caching name servers to pdns recursor 3.2 
(which is working very well), this has now been running for 4 days but 
in the last 24 hours we have seen the tcp listener stop answering 
queries on 2 seperate servers.  Our monitoring servers flag this up for 
us and restarting the recursor fixes it.

Now I know tcp isn't used that much but I was wondering if anyone else 
has experienced this, due to the size of the logs we would generate we 
have the quiet option set to yes in the config so only get basic logging 
(which showed nothing out of the ordinary).

In order to get the logging more detailed I tried the following :-

mkdir /local/log

edit /etc/syslog.conf and add the following line

local0.* /local/log/recursor.log

/etc/init.d/sysklogd restart

Then alter the recursor.conf file to log to local0 and turn off quiet :-

uncomment logging-facility and change it to 0
also change quiet=yes to no

/etc/init.d/pdns-recursor restart

But for some reason this slowed the caching name server down noticeably 
and caused 0ms queries to become 200-500ms sometimes more and when 
looking at the pdns processes in top the cache memory usage was very 
small and not moving up as expected.

This has only happened to one of 7 live servers at the moment and when I 
try and replicate on a test server the above does not happen so could be 
load through syslog level as the test server is very quiet.

Thoughts appreciated..


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