bind timeouts
Christian Hiris
4711 at chello.at
Tue May 18 16:12:25 PDT 2004
On Tuesday 18 May 2004 16:30, Matthew D. Fuller wrote:
> 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.
I found this in rfc 974 under 'Minor Special Issues'
[...]
Note that the algorithm to delete irrelevant RRs breaks if LOCAL has
a alias and the alias is listed in the MX records for REMOTE. (E.g.
REMOTE has an MX of ALIAS, where ALIAS has a CNAME of LOCAL). This
can be avoided if aliases are never used in the data section of MX
RRs.
[...]
Does it describe a situation like this?
IN NS ns.sample.org.
IN MX 10 mail
foo IN A 192.168.1.1
ns IN CNAME foo
mail IN CNAME foo
--
Christian Hiris <4711 at chello.at> | OpenPGP KeyID 0x941B6B0B
OpenPGP-Key at hkp://wwwkeys.eu.pgp.net and http://pgp.mit.edu
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