authority transfer question

[Philippe Champagne]

I have a test setup where I need to perform an experiment
but I am running with a problem regarding how to configure 
BIND for that matter.

I have a DNS server (let's say server A) which is the authority for "mydomain.com"
In it, it is pointing to another server (server B) as the authority for "www.mydomain.com"
Now the tricky part: I want to set another server (server C) as the actual
authority for "www.mydomain.com" without changing the configuration in server A.
Actually, my requirements are that the querier must resend its A request to server C.
How can I configure BIND on server B so that a DNS server making an A request
to server B will re-direct its question to server C?
If I put it in other words, what kind of packet should be returned by server B to 
satisfy this? 
Is this valid and possible?

Thanks
JPC