The DCA can be used to connect the MCMS server to any existing networked MCMS database.
Let's say you are working on MCMS websites for two different clients. Their websites have different configurations. You build two separate MCMS databases to cater for this purpose. You have only one development server, your trusty old desktop. Here's when the DCA can be useful, allowing you to switch between the different databases.
Or perhaps you have received a support call from a client running an MCMS website you created, and you need to analyze the content of the website to see if that is contributing to the problem. The client sends you the project files along with the backup of the entire database. All you need to do is to restore both the executables and the database, use the DCA to point your server to the database, and you are ready to go.
Another case is if you are working primarily on a development...