Question : NSLOOKUP does not return an response for a reverse zone request from a child domain

My environment has a parent domain (alpha.com) and a child domain (euorpe.alpha.com).  When I attempt an NSLOOKUP for a reverse zone while on a machine in the alpha.com domain, and the reverse lookup request is for a machine on the euorpe.alpha.com domain, I recieve an error: "dc01.alpha.com can't find 10.15.x.x: Non-existent domain".  It appears I cannot do a reverse lookup via nslookup for machines in child domains.  If I goto the europe.alpha.com domain, I can perform this reverse lookup with no problem.

What could cause this inability to query a pointer record in a child domains dns structure.

Answer : NSLOOKUP does not return an response for a reverse zone request from a child domain

Yes, if you want to be able to do reverse lookup from alpha.com.