Mailing List SIMS@mail.stalker.com Message #5643
From: Bill Cole <listbill@scconsult.com>
Subject: Re: MX pointing to CNames? (was: Backup mailer)
Date: Sat, 25 Mar 2000 21:00:12 -0500
To: SIMS Discussions <SIMS@mail.stalker.com>
At 4:30 PM -0500 3/25/00, billc@greenbuilder.com wrote:


> >At 11:38 AM -0500 3/25/00, billc@greenbuilder.com wrote:
>
> >> My MX records are presently
> >>
> >> mydomain.com MX 10 mail.mydomain.com
> >> mail.mydomain.com A xxx.xxx.xxx.1
> >>
> >> domain1.com MX 10 mail.domain1.com
> >> mail.domain1.com C mail.mydomain.com
>
> Bill Cole wrote:
>
> >Are those 'C's indicating CNAME records?
> >
> >That's bad. Never point an MX at a CNAME. Half the net won't understand,
> >and the rest shouldn't. It's *WRONG*
> >
> >If you really fee the need to have the mail.domainx.com names exist, make
> >them A records. There is no harm in having multiple names' A records share
> >an address.
> >
>
> > Lose the CNAME records. They are useless.
> >
> >If you MUST have them for some other reason, still make sure you don't
> >have MX records pointing at the CNAME names. That is bad. It is counter to
> >the DNS spec. It is unnecessary. Don't do it. It breaks things.
> >
> >
>
> I've never heard that before.  It seems to be working just fine.  I'm
> checking with the folks over on the QDNS list just to make sure, but if I
> remember correctly I got it from a fairly reliable source that it's an OK
> thing to do.
>
> I set it up that way because the IP address of mail.mydomain.com may change
> - it's been known to happen in the past.  It's sure a heck of a lot easier
> to have ONE place to change the IP address than having to change all of my
> DNS records.  So for me, it's not completely useless.

Then just point the MX records to mail.mydomain.com. You don't gain
anything by pointing them at mail.domainx.com. Really.

RFC's in support of this are 974, 1034, 1713, and 1912. Of course, the
people on the QDNS mailing list might disagree, but you are free to chose
your preferred authorities.


--
Bill Cole



Subscribe (FEED) Subscribe (DIGEST) Subscribe (INDEX) Unsubscribe Mail to Listmaster