out of place mx records.
Fr34k
freaknetboy at yahoo.com
Fri Oct 29 02:09:21 UTC 2010
----- Original Message ----
> From: Mark Andrews <marka at isc.org>
> To: Barry Margolin <barmar at alum.mit.edu>
> Cc: comp-protocols-dns-bind at isc.org
> Sent: Thu, October 28, 2010 9:49:46 PM
> Subject: Re: out of place mx records.
>
>
> In message <barmar-ED15C5.21262028102010 at news.eternal-september.org>, Barry
>Mar
> golin writes:
> > In article <mailman.585.1288263412.555.bind-users at lists.isc.org>,
> > Tony Finch <dot at dotat.at> wrote:
> >
> > > On Thu, 28 Oct 2010, Gregory Machin wrote:
> > > >
> > > > My question is why would "IN MX 10 mcvpemr01" and "IN MX
> > > > 10 mcvpemr02" be repeated trough the zone file surely this is
> > > > redundant ?
> > >
> > > Some hostmasters like to ensure that mail is not directed to hosts that
do
> > > not listen on SMTP. They prefer misdirected mail to be rejected
> > > immediately rather than waiting days for the sending system to time out.
> > > Some of my colleagues have this setup on the zones they manage
> > > (eng.cam.ac.uk and cl.cam.ac.uk).
> >
> > But configuring MX records won't necessarily accomplish this. It will
> > cause mail for all these hosts to be delivered to mcvpemr01 or mcvpemr02.
>
> And they can do a SMTP level rejection rather than waiting for the
> sending server to abandon sending the email due to multiple timeouts.
> Just return 550 for all mail directed to users at those hosts. It
> would be nice if we could standardise a MX target of "." as saying
> that this domain doesn't accept email e.g. "MX 0 ." the same way
> as "SRV 0 0 0 ." means that there is no service for the named
> protocol. That way the sending MTA or the MSA can reject the email.
>
Hello,
Is there an advantage to process email just to have the destination MX reject
it?
Why not use " IN MX 100 localhost" so the email doesn't even leave the source?
Or, am I confused?
> Every time it get suggested people shoot it down worrying about
> private nets that have addresses at "." or get worried about thousands
> of machines making A/AAAA queries for "." where the MTA doesn't
> check that the MX target is a valid host name.
>
> Mark
> --
> Mark Andrews, ISC
> 1 Seymour St., Dundas Valley, NSW 2117, Australia
> PHONE: +61 2 9871 4742 INTERNET: marka at isc.org
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