DNS woes (was Re: 50Hz vs 60Hz fixed drive speed ?)

From: Fred N. van Kempen <waltje_at_pdp11.nl>
Date: Wed Feb 18 06:59:03 2004

On Wed, 18 Feb 2004, Jay West wrote:

> Sellam wrote....
> > I think the reason it works when you receive messages from CC and not
> > directly from me is because my siconic.com domain does not rDNS resolve
> > properly (stupid upstream ISP
>
> As of late I have noticed that more and more major mail servers will not
> process mail from any server who's forward and reverse dns do not match
> exactly.
Yes, this is normal behavious these days.

 That's not a big deal, but the way some (AOL) are doing it, does
> violate RFC's. Specifically, even if the forward and reverses DO match, but
> the reverse lookup provides aliases as well, they will toss it. However,
> this breaks an RFC-specified way of handling delegation of subnets on uneven
> boundaries. *sigh*
Subnet delegation never worked well, so one simply should not do it
at all... just delegate at the class level. Alias processing is
pretty much never done well in MTA's, *especially* not for reverse
lookups. Simply dont rely on it, keep the mail server addressing
as simple as possible, using a single address, and a single DNS
mapping for it, without CNAME and PTR crap, because that will
slow down processing for your address as a result of multiple
lookups.

--f
Received on Wed Feb 18 2004 - 06:59:03 GMT