I have a client that wants two sites to have the ability to sync databases so information at Site A can be synced with Site B so the two sites can look at the same data.

I'm not even sure of the infrastructure required. Would a VPN required to connect the 2 databases or would an internet based database work ie/Site A to InternetDatabase and Site B to InternetDatabase. Each site copies data to it periodically and then the InternetDatabase syncs it and the Sites can then pull data down.

My other thought was something like Dropbox. If Site A and Site B use a Dropbox account to sync the ADT files etc can the database at each site then sync with those ADT files?

Thanks