The DAC, what is it? It is the Dedicated Administrator Console. Basically it is a way to connect to your SQL Server when all the other connections are tied up. But it takes a little bit of pre-planning so that you can use it when things go bad with your SQL Server. Let’s enable it so you can test using it and know that it is there in the future.
This is your “get out of jail free” card when the instance is completely unresponsive. A small amount of memory is dedicated to the DAC so that even if anything else is locked up, you have a chance to fix the problem short of a reboot.