Define a domains addresses sole in terms of another
bortzmeyer at nic.fr
Tue Jul 10 06:51:28 UTC 2007
On Mon, Jul 09, 2007 at 08:48:00PM -0400,
Barry Margolin <barmar at alum.mit.edu> wrote
a message of 46 lines which said:
> The RFC recommends against it for performance reasons, but doesn't
> prohibit it.
Yes, it does.
RFC 1034, 3.6.2 "Aliases and canonical names" :
> Domain names in RRs which point at another name should always point at
> the primary name and not the alias. This avoids extra indirections in
> accessing information. For example, the address to name RR for the
> above host should be:
> 126.96.36.199.IN-ADDR.ARPA IN PTR C.ISI.EDU
> rather than pointing at USC-ISIC.ARPA. Of course, by the robustness
> principle, domain software should not fail when presented with CNAME
> chains or loops; CNAME chains should be followed and CNAME loops
> signalled as an error.
BIND follows the advice, it works with CNAME chains. Not all resolvers do.
> It even mentions that resolvers must follow CNAME chains,
Not "must", "should".
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