How to Test Reverse Delegation?

Will DELETE_westes at
Fri Jan 7 01:36:20 UTC 2005

We want to handle reverse delegation for 16 IPs in a /28 classless domain.
Our ISP is willing to let us do this and will point their DNS to us as soon
as we are ready.    The problem is I don't see how we can test our reverse
delegation in advance of the ISP setting up their server.

As I understand it, the ISP will use a CNAME to rely on our server to
resolve specific IP  addresses.    Resolvers on the Internet will still try
to resolve any IP within the class C that contains our /28 range using the
ISP, not us.     When the ISP gets the query, it then privately retrieves
the answer from our server.

If we configure the /28 reverse lookup on our DNS, how do I test it?   Any
attempt to resolve using nslookup or dig is going to go to the authoritative
server, which in this case is the ISPs.    Even pointing at our local DNS
server directly, the DNS server is just ignoring its own configuration
information for the reverse IP and instead going upstream to the ISP.    I
need to find a way a DNS testing tool that will bypass the authoritative
server and instead try to get this information from the local server that
has been configured to handle the reverse lookup.   Does such a tool exist?


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