Viktor Dukhovni:
> On Thu, Oct 10, 2013 at 12:47:34AM +0200, Dominik George wrote:
>
> > Most tools, mainly libc's resolver, seem to ignore the Additional
> > section and resolve relevant names on their owns, explicitly asking for
> > the RR types they are itnerested in, and that's what seems to be
> > appropriate. Postfix, however, seems to rely on the Additional section
> > (if it has at least one RR for the MX host?), missing out on any records
> > that might be there but not cached by the uplink DNS server.
>
> Postfix does not look at additional records. However a local DNS
> cache on the machine running Postfix may well cache additional
> records from an upstream resolver, and if /etc/resolv.conf points
> at 127.0.0.1 (or perhaps its twin in the Postfix chroot jail), then
> Postfix may get those results in the answer section when it asks
> for the A records of MX hosts.
>
> > We do not quite see an situation where this might break badly, because
> > normally one MX result is to be considered as good as any other, but I
> > still wanted to ask whether this behaviour is intentional and the
> > limitations are known.
>
> This behaviour is not intentional, it is fictional.
Confirmed, Postfix looks at the answer section only. Claims to
the contrary are based on false speculation.
Wietse
