Date: Tue, 18 May 2004 09:16:21 +0200 From: Francois Tigeot <ftigeot@wolfpond.org> To: "Matthew D. Fuller" <fullermd@over-yonder.net> Cc: Cyrille Lefevre <cyrille.lefevre@laposte.net> Subject: Re: bind timeouts Message-ID: <20040518071621.GA78346@aoi.wolfpond.org> In-Reply-To: <20040518063753.GB2038@over-yonder.net> References: <0cc701c43704$fe189fc0$7890a8c0@dyndns.org> <200405110321.i4B3LFGI073037@bunrab.catwhisker.org> <20040511093634.GA41727@gits.dyndns.org> <200405180814.15854.4711@chello.at> <20040518063753.GB2038@over-yonder.net>
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On Tue, May 18, 2004 at 01:37:53AM -0500, Matthew D. Fuller wrote:
> On Tue, May 18, 2004 at 08:14:04AM +0200 I heard the voice of
> Christian Hiris, and lo! it spake thus:
> >
> > As far as i know MX records _must_ have an A record.
>
> RFC1035 states:
> MX records cause type A additional section processing for the host
> specified by EXCHANGE. The use of MX RRs is explained in detail
> in [RFC-974].
>
> 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.
>
> RFC2821 obsoletes 974, but says substantially the same in regards to
> CNAME's. So, by the RFC's it's allowed.
>
>
> For me, I think it's a bad practice. But, hey...
You're not the only one. RFC 1912 ( Common DNS Operational and
Configuration Errors ) states :
Don't use CNAMEs in combination with RRs which point to other names
like MX, CNAME, PTR and NS. (PTR is an exception if you want to
implement classless in-addr delegation.) For example, this is
strongly discouraged:
podunk.xx. IN MX mailhost
mailhost IN CNAME mary
mary IN A 1.2.3.4
--
Francois Tigeot
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