Linux-Hams archive - January 1997: Re: Sendmail and two smart hosts

Re: Sendmail and two smart hosts

Matthias Welwarsky (mdwgiidq@kerailya.tunkki.fi)
Mon, 13 Jan 1997 12:36:05 +0100


David Brooke wrote:
>
> In article <yzjwn.jyjchsnz@wirtgenamerica.com>,
> bzfpm.lcxpvgki@123.net (Dave J Brown) writes:
> >for themselves. i.e. if I ran gb7pit.ampr.org folks could 'subdomain' from
> >within there.... m1aax.gb7pit.ampr.org etc, then there could be a wildcard MX
> >for *.gb7pit.ampr.org ..... blah blah!
>
> Except that if these hosts had any other DNS records (such as A or CNAME)
> the wildcard MX record would be ignored. They are only valid for names
> which have no other records at all. This seems to be a little known
> aspect of DNS.
>
> [UK aside: This is why I have repeatedly disputed the "easier
> mail routing" argument for the <host>.<region>.uk.ampr.org names
> proposed at UKIP meetings despite nobody seeming to listen! An MX for
> *.<region>.uk.ampr.org won't work for hosts that have A records which
> is probably all of them.]

Well Dave, currently we are having the same discussion on the German
PR-News network, and I hope we'll come to a conclusion, soon. As the
German network is fully "unconnected" (well almost ;-), nobody uses the
"real" DNS at ucsd.edu. The idea I brought up there is to set up a set
of DNSs that have SOA-Records for several logical mail-domains with the
same naming scheme you proposed in your posting:
<host>.<region>.de.ampr.org.

For example, in the Rhein-Main area there will be a DNS that holds a
SOA-Record for rmn.de.ampr.org. This Record will have two MX records for
each host, one with low priority pointing to the mailserver of the
region, another one with a higher priority pointing to the host itself.
So mail will be delivered directly if the addressed host is known, and
and will be directed to the mailserver if not.

Additionally, to ease migration to the new scheme, each of these DNS
will hold an SOA-Record for ampr.org that contains CNAME-Records which
act as a pointer for the usual <call>.ampr.org.-names to the new names.
This way, these DNS will still resolve the old names into Ip-Addresses,
if needed. This will hopefully make everybody happy, because nobody is
forced into the new scheme at once ;-)

--
73s de Matthias