Dear Aditya,

You can surely appear for JEE Mains examinations irrespective of their +2 boards, whether it is state board or central board.

As far as admission in DU is concerned, you can totally go for admission process. There is no specific boards requirement. All the students from state boards or central boards have equal chance, you just have to score above the respective cut-off percentage.

Coming to NDA , the criteria for army wing is that the candidate should have passed his/her +12 examinations from the central board or any state board.