New CIDR reverse delegation scheme (was: `Re: reverse dns problems')

[Will Yardley]

Michael Kjorling wrote:

> Well, RFC 2317 is about the best solution I've been able to come up
> with as well that does reverse delegation on networks less than a /24
> in a relatively nice way without breaking anything. Create a new zone
> (it doesn't even have to be under in-addr.arpa, if some drainbead ISP
> wants to put it somewhere else :)) and use CNAMEs to point into that
> zone, then delegate the new zone while keeping authority for the /24
> one.
> 
> Properly implemented (using $GENERATE and a good zone-naming scheme)
> it isn't any more complex than standard classful reverse delegations
> (given that the ISP has a block bigger than the /24 assigned). The
> trick is to have the ISP and end-user agree on the zone name; apart
> from that I can see no obvious problems.

It's a bit messy though - having a CNAME and then a PTR - it would be a lot
nicer and cleaner if the reverse record would point to a PTR.  It seems as if
(without breaking anything) bind could include a way to internally allow a <
/24 zone to be created, and allow $GENERATE to be used for NS records
somehow.  That way, the NS records would point to the correct record but the
internal resolver would treat the zone file as if it were individual zone
files as far as resolution is concerned (ie it wouldn't think it was
authoritative for the whole class C.  That way it should be backwards
compatible but would still be easier to maintain and less of a hack.  I'm
sure there's an obvious reason that's not possible, but i can't think of it.

w