Installing DNS on member server over vpn

I have a site to site VPN with SBS2K3 server on site 1 and Win2K3 server on site 2. I can ping each site without any problems and even browse shared folders (by pointing to the DNS of the Win2K3 server to the SBS2K3 server). I ran DCPROMO and made the site2 server a Global Catalogue server, and would now like to install DNS on Site 2 so that if the VPN fails the users in Site 2 can still browse the internet.

When I try to install DNS on the second server it gives me many options and I am not sure which one to choose - I've never had to install more than 1 DNS server before. Can somebody shed some light on this please? Also, am I missing any steps?

Thank you