If DNN is in your DMZ, and Active Directory isn't, you'll need to open the necessary ports for authentication traffic to pass through your DMZ Firewall.  Windows ports like those are definite security holes so are most definitely closed by default.  I'd be very specific about the ports you open... be sure to only allow the DNN server IP and AD Server IP to use those ports.

OK I got it working, seems to be adding the users upon 1st login. How can I make it so authentication is passed thru and not prompting the users to input there network credentials? Also if this can't be done is there a way to prevent it from asking after the 1st time (save password checkbox does not work). Thanks for all your help.

-Cisco