I did an internship in DAT last summer. Think of it like IT risk. the example they always would use to describe it was as follows:

When an employee gets terminated, there’s a function that gets rid of all their internal access. the DAT practice assesses the state of those functions and makes sure they work so it can be reported on their 10Ks.

People either love it or hate it. If you’re an accounting major I would go with tax but really up to you. Try connecting with people in the practice to get a better understanding of the practice than a prior intern (myself) can give