Except the specific colleges and courses for which DU conducts an entrance examination, all others will admit students via the board marks(Best Four percentage). The ones conducting entrance will also consider the entrance test result. You moreover need a 55% qualifying marks in Grade 12 to apply for DU. You can check other details here:

https://university.careers360.com/articles/du-admission

You can further check the official site for more details here:

http://www.du.ac.in/du/index.php?page=ug-admission