Dear Pragya,

Sure ,you can pursue MCA from NITs as well as from top colleges after opting  BCA from IGNOU.As you know IGNOU is one of the largest Govt open Universities in India and the degrees offered by this university is equally valuable.

Well, to pursue MCA from NITs .. you need to take an Entrance Test called NIMCET.

Basic eligibility criteria: You should Graduate in B.A/B.Sc/BCA and have mathematics/statistics as one of the subjects and you should score min 60% in graduation  as well as in intermediate level.

To know more about this exam, refer to this link :

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

You can also pursue MCA from BIT(Birla Institute of Technology),after taking an Entrance Test conducted by them called BIT MCA exam.You should score minimum 55% in graduation and you must have mathematics and science at your intermediate level.

refer to this link for more details about BIT MCA courses:

https://www.careers360.com/university/birla-institute-of-technology-mesra/mca-course

Hope this helps !!

Best wishes !!