[Pdns-users] IXFR confuses dig, Godaddy

bert hubert bert.hubert at netherlabs.nl
Sat Dec 28 09:12:11 UTC 2013

On Fri, Dec 27, 2013 at 08:50:40PM +0100, Pierre Beck wrote:
> PowerDNS sends AXFR in three packets: SOA, RRs, SOA. This is fine with
> AXFR requests, but leads to problems with IXFR requests. One problem is

Hi Pierre,

You had me confused for a bit as we've previously had implementations that
actually cared about packet counts. But in your case, what you mean is that
we send three DNS *messages* (which could even fit in one packet, by the

> Another more serious problem occurs when serials don't match: dig keeps
> waiting for further data after the second SOA, which is actually a bug
> in dig, not in PowerDNS.

Well.. AXFRs should be atomic. If we change the SOA serial number over the
course of an AXFR, we are broken. But have you seen this? I think our code
retrieves the SOA just once, but I might be wrong.

> dig: ;; communications error to end of file
> vs
> pdns: TCP Connection Thread died because of STL error: Timeout reading data
> That shouldn't be a problem of PowerDNS, but it already affects
> compatibility, e.g. with Godaddy nameservers (maybe they used dig / BIND
> as a reference for their implementation).
> Anyways, wrapping the response in one packet instead of three would
> likely resolve both issues (using a MS DNS, which creates only one
> packet, doesn't confuse dig). Should I file this as a bug?

Well, I'm a bit confused since you appear to be reporting multiple issues,
multiple DNS messages and changing SOA serial numbers.  What actual bug are
you seeing specifically?


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> Regards,
> Pierre Beck
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