SCP for multiple forest for autodiscover

Dears, 

We have two different forests one called contoso.com and the other one called test.com 

# contoso.com have exchange server and autodiscover work fine with SCP 

# test.com only have split DNS and autodiscover record, if we want to configure user profile we must unplug the network adapter and connect to the network from outside 

How I can fix this issue for test.com ?