At 10:36 AM -0800 11/27/03, Hallam-Baker, Phillip wrote:
That is not true. RoadRunner has been using it to decide whether a connecting machine on port 25 is worthy of sending them mail, based (apparently) on whether the name resolved to matches .*(dsl|dial|dyn).*Many people prefer the LMAP proposals that deal with regular "forward" DNS than the MTA mark proposal that uses reverse DNS, because a usual domain owner has control over regular DNS and does not have control over reverse DNS.Absolutely, reverse DNS has not been generally considered a critical infrastructure, nobody uses it today except for debugging.
That's why DNS resolvers should always fall back to TCP when they get a truncated response. Using rDNS for anything significant without being prepared for a very large response is careless and stupid, but it is dominant practice and people ARE using rDNS in serious ways now without thinking about what they are doing with any sort of technical depth.The zones are prefectly stable, the problem is that the information in those zones is not maintained by the IP block holders to a sufficiently high quality. The other practical problem is that there are machines with several hundred thousand email domains parked on one machine.