Wildcards for MX and CNAME in same zone - allowed?

[Barry Margolin]

In article <a8adtj$cdv at pub3.rc.vix.com>,
Van Bemmel, Berend <bvanbemmel at kpmg.com> wrote:
>I have had two real answers to my question below, one was YES the other (you
>guessed it) was NO.

I didn't see that.  Everyone seemed to be in agreement that you can't do
what you want, but the ISP's explanation of why is wrong.

>Maybe I there is one thing I should add to the question and that the records
>are not in the zone example.com but in the zone anotherzone.net, this
>changes the behaviour of the wildcards, and makes them less harmfull I
>suppose because there is no more recursiveness involved.

It doesn't matter what zone they're in.

>
>So the zone file for anotherzone.net contains the following entries:
>
>*	MX 10		mailhost.example.com.
>*	CNAME		www.example.com
>
>Is this allowed (per RFC) and does it function? 
>Is my ISP right to refuse putting these records in my zone?

You can't have a CNAME record and an MX record for the same name.

Multiple wildcards *are* allowed, e.g.

*   MX 10 mailhost.example.com.
*   A     1.2.3.4

It's only the CNAME record that makes your combination invalid.

Are you sure you need the wildcard MX record?  It's only needed if people
will be sending mail to user at something.anotherzone.net.  If all mail will
be addressed to user at anotherzone.net (with no "something" prefix), you
don't need the wildcard MX.

-- 
Barry Margolin, barmar at genuity.net
Genuity, Woburn, MA
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