On Sun, Jul 05, 2015 at 08:17:03AM +0100, Ray Bellis wrote: > > Sure, CNAME is *defined* for all classes, but AFAIK there's no way to "jump" > out of one class into another using a CNAME.
No, that's correct. But if the point of using a class is to create a separate namespace, then the fact of class-independent RRTYPEs means you can't do that. As Paul Vixie notes, there appears to be some ambiguity with CNAMEs on this front, but as nearly as I can tell RFC 6672 makes this plain for DNAME. Imagine the alternative-resolution class FAKE. In the IN class, example.com has a DNAME entry pointing to example.net. What should happen when someone performs a query for QNAME localentry.example.com, TYPE AAAA, and CLASS FAKE? RFC 6672's description of the algorithm does not use CLASS as a distinguishing criterion. So, I think the answer is the DNAME processing should return the results for localentry.example.net, regardless of the class. As a consequence, CLASS does not work to provide different completely independent namespaces, and therefore co-ordination across the class registrations will be necessary. In effect, CLASS doesn't work. At least, that's my reading of the RFC. I'd be pleased to be wrong. Best regards, A -- Andrew Sullivan a...@anvilwalrusden.com _______________________________________________ DNSOP mailing list DNSOP@ietf.org https://www.ietf.org/mailman/listinfo/dnsop
