> The IN-ADDR.ARPA delegations for RFC1918 space are just like any > other block. You'll just end up hitting IANA's blackhole servers, > and not all that much, the cache times are one week.
In theory, yes. In reality there are quite a few resolvers that, apparently, do not receive the delegation response and continue to hit the roots with PTR queries for RFC1918 space. Recent measurements at a single instance of an anycasted root server show that at least 250 such resolvers generate between 60-120 RFC1918 PTR queries/sec. Duane W.