Proper CNAME interpretation

[John Payne]

On Sep 14, 2011, at 4:35 PM, Ronald F. Guilmette wrote:

> Is there a rule that says how a resolver should behave in cases where
> there is both an A record and also a CNAME record for the same FQDN?
> Which one should take precedence, the A or the CNAME?


RFC 1034, Section 3.6.2: "If a CNAME RR is present at a node, no other data
should be present; this ensures that the data for a canonical name and its
aliases cannot be different. This rule also insures that a cached CNAME can
be used without checking with an authoritative server for other RR types."



via http://www.bind9.net/BIND-FAQ

DNSSEC changes that a little in as much as a node can have an RRSIG with a CNAME, but what good is a rule without an exception? :)