Not exactly sure what you are trying to achieve here ... 

DNN is quite happy to accept domain aliases for any domain.
And you can setup a portal associated with any such domain.

But you still need to define an alias for each domain in IIS.
IIS does not support wildcard domains so if you want to listen for 
test.com   and   david.test.com  you will need to declare an alias for both inside IIS

The only exception to this rule is if you have a STATIC IP on your IIS and are able
to configure a IP only binding - in which case you would rely on DNS to handle the
wild card mapping.

Westa