Bug#342619: Possible exim retry bug (Re: master mail problems -- help needed)

[Jeroen van Wolffelaar]

On Sat, Dec 17, 2005 at 04:07:51PM +0100, Marc Haber wrote:
> On Fri, Dec 09, 2005 at 01:12:56AM +0100, Jeroen van Wolffelaar wrote:
> > I'm quite sure it's an exim bug, but haven't quite nailed it yet. The
> > bug has been witnessed positively both on master.d.o and on
> > one mailserver I maintain. Interestingly, it doesn't seem to be IPv6
> > related (or maybe there are two bugs).
> 
> It might be DNS related. Can you comment about
> http://www.exim.org/mail-archives/exim-users/Week-of-Mon-20051212/msg00196.html
> please?

That sounds very much like the cause of this bug. It's also possible
even for IPv4 issues like the one in my original bugreport, as also in
that case, TTL's were distinct, and indeed, the situation could arrise
that a DNS query would give only partial results in the additional
section, because of the setup of the involved DNS servers.

So, it seems like the logic error is in that the additional DNS section
is believed to be complete, which is not at all guaranteed to be true --
it can be partial for any reason.

Thanks a lot for finding the (IMHO) most logical cause of this bug,
which according to Ockham's razor, is the cause of this bug. I tried
looking into the code etc, but simply failed to find the reason and
wouldn't easily have found this at all...

If you have any further questions, please ask,
--Jeroen

-- 
Jeroen van Wolffelaar
Jeroen at wolffelaar.nl (also for Jabber & MSN; ICQ: 33944357)
http://Jeroen.A-Eskwadraat.nl