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

[Marc Haber]

On Sat, Dec 17, 2005 at 04:17:45PM +0100, Jeroen van Wolffelaar wrote:
> 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.

I agree with that. I filed the message for exim-users before reviewing
your bug report, so I'll have to mention the possibility of this
happening in a v4-only setup later. But first I'll wait for Philip to
comment.

> 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.

Right.

> Thanks a lot for finding the (IMHO) most logical cause of this bug,

Florian had a big part in this, we spent the better part of this
afternoon over DNS queries and DNS output on IRC. Without his help,
this wouldn't have been possible.

Greetings
Marc

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