Here is a good article on split DNS from ISA Server.org
Bacially the issues is when I’m on the local network I want to resolve my home automation systems IP with the local IP and when accessing via the WAN port I want to resolve the public.
So in the iPhone app server field I put in: alarmsystem.jakked.net
When I’m behind the ZS I need alarmsystem.jakked.net to resolve as 10.10.11.xxx
When on the net the DNS should resolve alarmsystem.jakked.net as xxx.xxx.xxx.xxx