If you wish to take the admission in NITs for MCA programme then you need to appear NIMCET Entrance Exam, To apply for the Exam you should be passed B.Sc. / B.Sc. (Hons) / BCA / BIT of minimum three years full-time from a recognized University with Mathematics/ Statistics as one of the subjects. You can check the further eligibility to apply for the exam with the given below link.

https://it.careers360.com/articles/nimcet-eligibility-criteria

Good Luck!