[dnsext] Name equivalence: Another no protocol change solution

[Alex Bligh <[e-mail]>]

The problem to me seems to be divided into (at least) two:

1. Apparent pseudo-regulatory requirement to ensure TLDs operate with
   recursive sameness. This is making TLD1 == TLD2.

2. Requirement within a TLD for some sort of equivalence (possibly not
   recursive) but notably not driven by a third party's perceived
   requirements. This is making foo.TLD == bar.TLD.

Problem 1 can, it seems to me, be solved by DNAME. DNAME only doesn't
do the job when there is a record at the apex, because DNAME+CNAME
can't coexist. Few if any TLDs have records at their apexes.

Problem 2 cannot in general be solved by DNAME (DNAME+CNAME problem),
as foo.tld may well exist. This can, however, in general be solved
by provisioning algorithms.

It is not particularly neat solving what looks like one problem with
two solutions, but closer inspection suggests the problems are
in fact different.

-- 
Alex Bligh