Date: Tue, 18 May 2004 09:30:27 -0500 From: "Matthew D. Fuller" <fullermd@over-yonder.net> To: Randy Bush <randy@psg.com> Cc: cyrille.lefevre@laposte.net Subject: Re: bind timeouts Message-ID: <20040518143027.GE2038@over-yonder.net> In-Reply-To: <16554.7288.281205.464222@ran.psg.com> References: <20040518063753.GB2038@over-yonder.net> <200405180804.i4I8477E019740@gw.catspoiler.org> <16554.7288.281205.464222@ran.psg.com>
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On Tue, May 18, 2004 at 07:23:52AM -0700 I heard the voice of
Randy Bush, and lo! it spake thus:
> >> RFC974 says:
> >> There is one other special case. If the response contains an
> >> answer which is a CNAME RR, it indicates that REMOTE is actually
> >> an alias for some other domain name. The query should be repeated
> >> with the canonical domain name.
> >
> > That covers the intial lookup, meaning that a CNAME pointing to an MX is
> > legal.
>
> no. it means an MX referring to a CNAME which resolves to an A
Not by my reading.
The first step for the mailer at LOCAL is to issue a query for MX
RRs for REMOTE.
[...]
If the response contains an answer which is a CNAME RR, it
indicates that REMOTE is actually an alias for some other domain
name. The query should be repeated with the canonical domain name.
which covers the case:
foo IN CNAME bar
bar IN MX 10 mail
mail IN A 127.0.0.1
not the case:
foo IN MX 10 bar
bar IN CNAME mail
----------------
But, as I came across in a completely seperate quest (today is Bizarre
Coincidence Day, boys and girls!), see RFC2181 §10.3:
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.
Of course, 2181 is a _Proposed_ Standard, for whatever value you may
choose to assign to that classification.
--
Matthew Fuller (MF4839) | fullermd@over-yonder.net
Systems/Network Administrator | http://www.over-yonder.net/~fullermd/
"The only reason I'm burning my candle at both ends, is because I
haven't figured out how to light the middle yet"
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