[idn] internal DNS server behavior is irrelevant

["Adam M. Costello" <idn.amc+0@nicemice.net.RemoveThisWord>]

We can stop discussing what authoritative DNS servers do internally when
deciding how to answer a query, because it's completely irrelevant.
An authoritative DNS server is already able to use whatever arbitrary
method it likes to decide how to answer queries (because it is the
authority--its answers define the namespace), and the proposed IDNA does
nothing to change that.

The only relevant issue is how *other* machines (DNS caching servers and
end hosts) decide whether two names are the same.  This is the algorithm
that is used to decide whether a query can be answered from the cache,
or whether a link has already been visited, or whether the name used
to contact a web server matches the SSL certificate presented by that
server.  Because this matching algorithm is performed locally (without
doing a DNS lookup) it must be well-known and standard.

Having authoritative name servers do extended matching internally can
confuse applications (because they effectively create alternate names
for servers that the servers themselves might not recognize--think
virtual web hosts).  Getting around this problem would apparently
entail extending the application servers inside the zone to understand
the additional matching.  Each zone can decide whether it's worth the
trouble to go down that road.  But that is all orthogonal to IDNA.

To reiterate:  We can stop discussing localized matching rules, because
IDNA does nothing to encourage or prevent them.  The relevant issue is
the single well-known matching rule.  Can we go ahead with the one in
IDNA, or do we need to prohibit simplified code points while the TC/SC
issue is settled (I hope not)?

AMC