domain name system - Redirect prefixed site named in DNS Forward Lookup Zones in Windows DNS Server

I have named a domain internally in my forward lookup zone in windows dns for my internal network. There is one prefix that i need for it to look up using the named external DNS (like google DNS 8.8.8.8). I host many intranet sites/locations, but i dont host our public web server in house. The issue is that we use a CDN, so the IP is never static, and I cant define it with a A record.

For Example:

Forward Lookup Zone Defined for: Contoso.com
department1.contoso.com = 192.168.x.5  
department2.contoso.com = 192.168.x.6  
www.contoso.com = [dynamic ip that needs to be looked up by 8.8.8.8]
contoso.com = [dynamic ip that needs to be looked up by 8.8.8.8]

I am stumped.
If i dont define www at all, my dns lookup comes back without an ip