Forwarding reverse DNS queries

[Mark_Andrews at isc.org]

> A customer of mine is having issues with their reverse DNS. The 
> situation is this:
> 
> They lease a block of IPs from me. The customer has his own DNS servers 
> (two of them). Forward lookups work fine, but reverse lookups don't work.
> 
> I understand what the problem is--reverse lookups are being directed to 
> my servers since I own the IP block in question.
> 
> The question is: How do I forward reverse DNS lookups for a specific 
> block of IPs to his servers?

	What size block do you have?
	What size block does you client have?

	What you have to do depends upon the answer to those queries.

	Basically if the client delegation is less than a /24 then
	see RFC 2317.  If you have the containing /24 then you do
	the delegation otherwise your parent does the delegation.

	If the client delegation is a /24 or bigger traditional
	delgation techniques should be used.  If you have the
	enclosing /16 for /17-/24 (or /8 for /9-/16) then you do
	the delegation otherwise your parent does the delegation.
	RIRs are setup to do this (e.g. you have /20 and your client
	has a /24).
	
	Mark
--
Mark Andrews, Internet Software Consortium
1 Seymour St., Dundas Valley, NSW 2117, Australia
PHONE: +61 2 9871 4742                 INTERNET: Mark.Andrews at isc.org