There is only one national level exam called NIMCET conducted to provide admission in MCA program in NITs. Also, there may/may not be other private and state level entrances and the eligibility criteria will be varied for all as well. So if you wish to get seat in NITs then better to clear NIMCET exam with decent rank. To know more about NIMCET exam, you can go through the below link -

All about NIMCET

Good Luck!!!