CNAME, MX and more

[Michael Kjorling]

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On Feb 4 2002 10:04 +0100, Paco Orozco wrote:

> Hiya,
>
> Imagine this scenario:
>
> Scenario 1:
>
> nmg.hola.com.		IN	A	10.0.0.1
> nmg.hola.com.		IN	MX	10	mailhost1.hola.com.
> 			IN	MX	20	mailhost2.hola.com.
>
> Is this possible??? Is there any mistake?

You don't define A records for mailhost[12].hola.com. Other than that
there is no problem with this DNS data, syntactically speaking.


> Scenario 2:
>
> nmg.hola.com.		IN	CNAME		server.hola.com.
> nmg.hola.com.		IN	MX	10	mailhost1.hola.com.
> 			IN	MX	20	mailhost2.hola.com.
>
> Is this possible??? Is there any mistake???
>
> Thanks

This must be one of the most frequently asked questions around here.
Try searching for "CNAME and other data" in the archives. RFC 1034
section 3.6.2:

"If a CNAME RR is present at a node, no other data should be present;
this ensures that the data for a canonical name and its aliases cannot
be different."

This restriction has been lessened recently in that SIG, NXT and KEY
records are allowed alongside CNAMEs, for DNSSEC purposes (though I
don't remember which exact RFC codifies this off the top of my head).

Any questions?


Michael Kjörling

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