CNAME/MX question...

[Kevin Darcy]

If you have a CNAME, that should be the *only* entry in DNS with that owner
name. In fact, it's illegal to have other records with the same owner name as a
CNAME. Any mail server obeying the RFC's will translate that CNAME and find the
MX records, etc. under the "canonical" name (i.e. the target of the alias).


- Kevin
Vyto Grigaliunas wrote:

> Hi...
>
> Thanks for the reply...
>
> Sorry I wasn't specific enough...
>
> Here's the situation...
>
> I've got the following CNAME in our primary domain pointing to a system in a
> subdomain :
>
> fnneta.fnal.gov.   IN   CNAME   fnneta.test.fnal.gov.
>
> The authoritative server for the "test" subdomain has the following records
> for fnneta.test.fnal.gov :
>
> fnneta          IN      A       131.225.2.1
>                 IN      MX      0       fnneta
>                 IN      MX      100     heffalump.fnal.gov.
>                 IN      MX      200     woozle.fnal.gov.
>
> I guess my question concerned mail addressed to vyto at fnneta.fnal.gov -
> SMTP/sendmail should find the MX records associated with the target of the
> CNAME, in this case fnneta.test.fnal.gov - I shouldn't need to associate the
> MX records with the CNAME (which to me doesn't seem right), i.e. -
>
> fnneta.fnal.gov.   IN   CNAME   fnneta.test.fnal.gov.
>                              IN   MX     0    fnneta.test.fnal.gov.
>                              IN   MX     100  heffalump.fnal.gov.
>                              IN   MX     200  woozle.fnal.gov.
>
> It seems to work (and I don't think it breaks any of the rules), but I just
> wanted to make sure that this was something that wasn't recommended practice
> with possible non-expected results...
>
> > [Why eeyore, heffalump, and woozle, but no pooh or piglet???  ;->]
>
> Sorry...I didn't name them...not a Pooh fan...now Homer Simpson...there's an
> actor ;-)
>
> Thanks...
>
> Vyto
>
> ----- Original Message -----
> From: "Joseph S D Yao" <jsdy at cospo.osis.gov>
> To: "Vyto Grigaliunas" <vyto at fnal.gov>
> Cc: <bind-users at isc.org>
> Sent: Thursday, September 07, 2000 11:23 AM
> Subject: Re: CNAME/MX question...
>
> > On Thu, Sep 07, 2000 at 10:10:26AM -0500, Vyto Grigaliunas wrote:
> > > I apologize in advance if this is not the proper forum for this
> question...
> > >
> > > If SMTP mail is being addressed to a CNAME record and an MX record is
> desired
> > > to be associated with the CNAME, can I associate an MX record with the
> CNAME
> > > or will SMTP/sendmail follow the CNAME to the target canonical name and
> find
> > > the MX record(s) associated with that target canonical name.
> >
> > Proper forum.
> >
> > Your question is not clear.
> >
> > If you are addressing e-mail to vyto at grigaliunas.fnal.gov, and in the
> > fnal.gov zone, the CNAME for grigaliunas is woozle.fnal.gov:
> >
> > grigaliunas IN  CNAME woozle.fnal.gov.
> >
> > then this will work fine.
> >
> > However, if you are sending e-mail to vyto at fnal.gov, and the mail
> > server is heffalump.fnal.gov, but you put another name in the MX record
> > whose CNAME is "heffalump":
> >
> > grigaliunas IN  CNAME heffalump.fnal.gov.
> > @ IN  MX grigaliunas.fnal.gov.
> >
> > then this is NOT good.  The target of the MX record may not be a name
> > that has a CNAME record.
> >
> > [Why eeyore, heffalump, and woozle, but no pooh or piglet???  ;->]
> >
> > --
> > Joe Yao jsdy at cospo.osis.gov - Joseph S. D. Yao
> > COSPO/OSIS Computer Support EMT-B
> > -----------------------------------------------------------------------
> > This message is not an official statement of COSPO policies.
> >
> >