Dynamic DNS registration fails over NAT

What happens when a client tries to register its IP address to its Primary DNS server? .. What i really wants to understand is that whether a DC will try to contact the client before registering client record in its zone? To check whether the client machine is active in network.

We have a client machine in a different network other than our corporate network and communication is configured via NATing . We have opened all the necessary ports and we have successfully added client machine to our corporate domain. 

But the DNS record is not getting registered in our corporate DNS server. Problem is like client is trying to register its internal IP address to the corporate network instead of its NAT IP. 

Primary DNS of the client machine is our corporate DNS server  (NATed IP).

Client's internal IP is in series 192.168.x.x and NAT IP is in the range 172.18.x.x and the internal IP of the client is not pingable from our corporate network.