NSlookup Issue

I have 2 domains, domain A and Domain B. Both domains have separate DC's with DNS hosted. From the DC in Domain A, I am able to do a NSLookup on a Secondary Zone from Domain B, but when I try do a NSLookup on the secondary zone in Domain B from client PC in Domain A, I get the following response.

> Memberserver123
Server:  DCindomainA
Address:  x.x.x.x

DNS request timed out.
    timeout was 2 seconds.
DNS request timed out.
    timeout was 2 seconds.
*** Request to DCindomainA timed-out

Reverse the scenario coming from a client PC in domain B on Secondary zone in Domain A and all is fine. Please Obi Wan you my only hope...