[Pdns-users] Error with master slave replication

Bill Pitz bill at pitz.net
Thu Aug 27 15:15:41 UTC 2009

Piotr Przybył wrote:
>> We are having trouble with master/slave replication with a couple of our
>> large zone files.  This is PDNS-native replication, not database
>> replication.
>> Replication is working fine to one of our slaves, but not to the other. 
>> The broken slave continuously throws these errors when the AXFR of the
>> zone is attempted from the master:
> Could you specify if this happens for every zone for this single slave
> or only for "large" ones?
> Have you checked if this slave is allowed to do AXFR? Master's config,
> allow-axfr-ips?
The problem occurs for the "large" zone.  The smaller zones update just 

And yes, this slave is allowed to AXFR -- it retrieved the larger zone 
fine initially, and a few times after that.  Then it stopped.  I set up 
an additional slave and it has the same problem.  As it stands now, two 
of the slaves are in the same datacenter with the master and one is in a 
different facility.  Only the slave in a different facility is able to 
regularly transfer the large zone without issue.  I have a feeling that 
there is some sort of timeout occurring with database access when the 
slave is local, but the remote slave has a natural "throttling" due to 
its distance from the master.
> You may login to slave machine and try to dig @XX.XX.XX.XX xyzzy.net AXFR
Yes, manual AXFR requests work from all of the slaves, every time.  No 
>> Aug 26 14:46:09 dns2 pdns[16674]: AXFR started for 'xyzzy.net',
>> transaction started
>> Aug 26 14:46:31 dns2 pdns[16674]: Unable to AXFR zone 'xyzzy.net' from
>> remote 'XX.XX.XX.XX': Remote nameserver closed TCP connection
>> Aug 26 14:46:31 dns2 pdns[16674]: Aborting possible open transaction for
>> domain 'xyzzy.net' AXFR
> Take a look at master's logs as well. You may find a reason why it
> closes the connection.
I've checked there as well, and unfortunately nothing of interest 
appears in the master's logs, even with logging increased to the maximum.

Any other ideas?


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