backup mail server

Terrence Koeman root at
Wed Oct 31 08:36:10 UTC 2001

> also, re: no CNAME for MX... another thing that comes to mind...
> a buddy of
> mine uses as a mail server system (like hotmail, for
> example), and per their instructions, he was to change his MX record to
> point to, as such:
> ;mail server
>    MX 10 mail
> mail   CNAME
> ....and it works, as we, with out basic understanding, would
> expect.  is this
> technically wrong?  is this an oversight/error that Bind v8.2.5
> (NT) allows
> and accepts (for example, go to a URL with backslashes, such as
> http:\\  or is it technically "acceptable" as far as bind
> concerned, though bad form?
> thanks again...

( - section 10.3)

10.3. MX and NS records

The domain name used as the value of a NS resource record, or part of the
value of a MX resource record must not be an alias.  Not only is the
specification clear on this point, but using an alias in either of these
positions neither works as well as might be hoped, nor well fulfills the
ambition that may have led to this approach.  This domain name must have
as its value one or more address records. Currently those will be A
records, however in the future other record types giving addressing
information may be acceptable. It can also have other RRs, but never a


Terrence Koeman

Technical Director/Administrator
MediaMonks B.V. (

Please quote all replies in correspondence.

> "phrogg" <fake at> wrote in message
> news:9rn73v$15k at
> > Hi,
> >
> > I'm trying to set up a backup mail server.  However, either I don't
> how
> > it works (in action), the mail server is broken, or I didn't do the
> > correctly.  This is what I have in my zone file:
> >
> > ;system mail server
> >   MX 10 mail
> >   MX 20 mail2
> > mail  CNAME @
> > mail2  A
> >
> > From what I understand about how email servers work, they first
> determine
> > the MX records.  My dns server would return the addresses for "mail"
> > "mail2".  Then the mail server would try to deliver to the address at
> "mail"
> > then, if that fails, the address at "mail2", since it has a higher
> > preference value.  When I shut down my mail server (located at
> and
> > have someone send a test email, it gets bounced back to them, instead
> > being sent to the address at "mail2".
> >
> > So, my question is this: are my dns records set up properly?  Is there
> more
> > I need to do?  I'm trying to narrow down by eliminating what's
> right so I
> > can figure out what's wrong.
> >
> > Thanks,
> > phrogg

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