Good summary, Tony. Here's my perspective:
Tony Hansen wrote:
Tony Hansen wrote:
* levine-adsp-00 provides a superset of methods for *how* to
determine if the domain exists: the NXDOMAIN test and the "check MX &
A/AAAA" method from SMTP. It leaves it up to the implementation to
choose the algorithm that works best for it.
While I agree that, in practice, either practice is "good enough", I
don't see a good reason for specifying two different ways of doing this
test. The closest to this that I have seen is Tony Finch's comment that
there might be some resolvers that don't distinguish NXDOMAIN from (for
example) a no-data result, but I haven't seen anyone cite an example of
this so I don't know whether this is a hypothetical or real consideration.
Since ADSP is a security-related specification (or, at least, this is a
WG in the Security Area), I think it's beneficial to be as precise as
possible about how the ADSP Check is done.
-Jim
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