Hi Somnath!

The procedure is same for admission in NIT durgapur and IIIT kalyani and that is through entrance exam JEE MAIN followed by counselling. You have to get the cutoffs for respective colleges to get a seat in them. The last year cutoffs for IIIT Kalyani was as follows:- Computer Science and Engineering    Gen(open rank)-  861 and  (close rank)- 35799.

For NIT durgapur the cutoffs were:- Computer Science and Engineering Home state quota- GEN(open rank)- 1638  and (close rank)- 15553. Other state quota:- GEN(open rank)-  4377   and  (close rank)-  8516.

You can know your college by this:- JEE Main College Predictor 2019 - based on your JEE Main Rank

I hope it helps.