Re: [Exim] Address rewriting vs. CNAME records?

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Autor: Vadim Vygonets
Data:  
A: exim-users
Assumpte: Re: [Exim] Address rewriting vs. CNAME records?
[revised]

Quoth Giuliano Gavazzi on Thu, Feb 06, 2003:
> well, it would probably be more correct to say that (the host)
> bar.my.dom. is the only mail exchanger for the domain of the same
> name..


This is the correct terminology, indeed. But host names are also
domain names, so a host pointed to by the domain name bar.my.dom
is the MX record for itself's domain.

> this is why MX records should never be omitted, the left and
> right hand side are never the same thing.
> This is in RFC 7821.


Where does RFC 2821 say you shouldn't omit MX records? It
clearly states that an omitted MX record is an implicit MX record
of priority 0 pointing to itself.

And what do you mean by them not being the same thing? Consider:

foo    IN    MX    10 foo
foo    IN    A    1.2.3.4


The A record gets looked up whether the MX record exists or not,
and for the same reason. So how is the name on the LHS different
from the one on the RHS?

Vadik.

--
When in doubt, be yourself. And if that fails, su root.