We don't seem to have resolved the question of whether the ADSP should
define a specific existence check, or just say that you should check
but leave the definition for other places.
Personally, I think it's severe mission creep to try to define an
existence check. It's straightforward to check for a NXDOMAIN or
NODATA result, but I see no reason to think that such a check has the
semantics an ADSP user would want.
To touch on some of the issues (and try not to rehash them all), the
majority of A and AAAA records don't name domains used in mail and you
can't check short of sending a test message and waiting a week to see
if it bounces, there's many ways a name can exist but again not for
mail (what if there's just a TXT record), and any check we defined
would just be wrong if, e.g., next year we make MX . the no-mail
standard.
So I like Arvel and Wietse's approach, say to do it but don't try to
define it since any definition would be wrong. Other thoughts?
R's,
John
Arvel said, two weeks ago:
Hence, the wisdom of Wietse's solution which is to have the spec assert
that ADSP is to be applied only to Author Domains which exist in DNS.
This nicely eliminates the need for language like "you MUST (or SHOULD)
do a DNS check" thus satisfying (one would hope) one side of the debate
while at the same time requiring the acquisition of the data which
"domain does not exist" needs - thus satisfying the other side of the
debate.
It's beautiful. I note with great concern that my opponents in this
debate have not commented on Wietse's proposal.
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