looking for reference to correct behavior

[Maria Iano]

My apologies if this is considered to be too off-topic.

I have a situation where my company uses a number of servers with a  
commercial DNS implementation (in addition to our BIND servers). The  
other implementation is Windows DNS, and there is some behavior that I  
do not think is acceptable, but which the vendor claims is acceptable  
behavior. I really want them to fix this bug (as I consider it), but  
first I need to get general agreement that it is a bug. I will be  
looking through the RFCs as much as I can time for, but haven't found  
what I need yet. Since my next meeting with the vendor is tomorrow, I  
thought I would also ask if anyone can already point me to a relevant  
RFC or other reference.

Here is the behavior that I think is not acceptable.

We have configured a zone on the windows server - dmz.example.com.  
This zone contains an A record for foo.dmz.example.com with IP address  
10.240.240.240. The zone example.com is hosted elsewhere and contains  
a CNAME record foo.example.com pointing to foo.dmz.example.com.

If the cache has just been cleared, and a client asks the WIndows DNS  
server for foo.example.com, it has a forwarding server to which it  
forwards the request. The forwarding server hands it back the CNAME  
record but it also hands back an A record for foo.dmz.example.com  
pointing to an incorrect IP address 192.168.240.240. The Windows DNS  
server accepts this A record for foo.dmz.example.com with an incorrect  
IP address into its cache, and hands out that incorrect information to  
the client. Even though it concurrently has dmz.gannett.com configured  
on it as a primary zone with a record for that same owner name  
pointing to a different IP address.

I believe it shouldn't do that. Since it hosts dmz.example.com as a  
primary zone, I think it should discard that bad A record and hand  
back its own.

The vendor's argument is that it should blindly trust the forwarding  
resolver.

Can anyone point me to an RFC or reference about this?

Thanks,
Maria