This is one of the new feature released with SQL Server 2008 R2. I know it’s late to cover this topic. It has greater flexibility and easy of implementation for database perspective. I could say it’s a build which has all database & instance level objects for implementation, just run the build and get the database work done, just simple like that. I’m not sure why Microsoft chosen same acronym for Data tier applications as DAC is also know as Dedicated Administrator Connection, lets not dig into it, only Microsoft can answer!!