Following is the age criteria:-
- For NDA 2, candidates must have born not earlier than January 2, 2002, and not later than January 1, 2005.
- For NDA 1, candidates should be born not earlier than July 2, 2001 and not later than July 1, 2004.
You are born in Jan 2001, so therefore you are not eligible for the NDA 2020.
Hope this helps. Thank you.
According to the basic eligibility criteria for NDA exam you need to be minimum of 16.5 year old or maximum your age should be 19.5 year, So here according to your date of birth you are eligible for now, for more details kindly refer the link given below:
Best of luck