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"brian" == <brian.wilkinson@bt.com> writes:

brian> Can anyone confirm whether DSL (and dial) providers are brian> required to provide matching forward and reverse DNS for brian> the address pools or is a wildcard in the reverse zones brian> sufficient? There's no requirement. Though your customers might appreciate it if reverse lookups worked for the IP addresses. Sometimes applications will make life difficult for hosts that don't have working reverse DNS. For instance a client that initiates an SMTP connection may be considered a spam source if there's no sensible answer to a reverse lookup of the client's address. And as Peter has said, wildcards are probably not a good idea for this sort of thing. It could also break when the application does a forwward lookup of the name returned by a reverse lookup. The BSD r- protocols -- which I hope nobody uses any more -- do this to decide if the client is who they claim to be and therefore determin if the client is trusted or not.