[dns-wg] Replacing reverse zone delegations by DNAMEs

I don't know whether this is the most appropriate forum to raise
this issue --- but if RIRs can be persuaded to support the alternate
form of reverse zone delegation suggested here, perhaps other
authorities would do the same.

Fragmentation of IPv4 space leads to organisations having lots of
little reverse zones, each of which requires: managing the contents,
maintaining the registration, organising official slaves, DNSSEC
signing ... There is much uneconomic effort involved.

Locally we have been using a scheme to map such reverse lookups into
a single common zone, described at

  http://people.pwf.cam.ac.uk/cet1/prune-reverse-zones

To take full advantage of this, however, requires promoting DNAMEs
into the parent reverse zone.

Logically, administrators of such zones ought to be delighted to
replace delegations (multiple NS records, maybe DS records as well)
with a single DNAME. But of course it has not been standard practice
to support that.

As DNAMEs do not redirect the name itself, there would be a problem
for reverse zones containing significant records at the apex, e.g.
PTR records pointing to a gateway host. (I think that practice,
recommended in RFC 1033, has pretty much fallen into disuse.) If the
IETF DNSEXT WG ever get their act together on "XNAME"/"CNAME+DNAME",
that would cover that particular point, but meanwhile no-one would
be obliged to use DNAMEs if they didn't want to.

Anyway, I would welcome opinions on this idea.

-- 
Chris Thompson               University of Cambridge Computing Service,
Email: cet1 at ucs.cam.ac.uk    New Museums Site, Cambridge CB2 3QH,
Phone: +44 1223 334715       United Kingdom.