Nitesh,

There is common form to get admission in dtu/nsit/iiitd/igdtu.

A certificate issued by NCT delhi will only be gone consider for taking admission if you belong to DELHI region.

One must carry central category certificate issued by NCT delhi for taking advantages of delhi obc quota otherwise one will be consider as OBC outside delhi.

So if you are outside Delhi region then your obc certificate will be accepted by the committee.

Hope it helps.