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@ucs.cam.ac.uk New Museums Site, Cambridge CB2 3QH, Phone: +44 1223 334715 United Kingdom.