Hello,


First of all you will have to appear in JEE mains examination and admission in architecture is based in JEE mains paper 2 marks.
Now, for admission in NITs one should have secured atleast 75% marks in class 12th examination,or be in the top 20 percentile in the 12th class examination conducted by the respective boards. For SC/ST students the qualifying marks is reduced to 65%.

I hope this helps.