Class 12-science

This is the All India Entrance Examination which is conducted by the UPSC (Union Public Service Commission) every year in the months of April and August as NDA1 and NDA2.
The basic eligibility criteria which needs to be met by the applicants in order to apply for the NDA are :-
1. You should be an Unmarried Male Indian.
2. Your age should be well within 16.5 to 19 years.
3. You should be a minimum 12th pass from any recognized state board or school. No minimum percentage is required.
4. You must have studied Physics and Mathematics if you want to apply for the Air Force and Naval wings.
5. Also physical and mental fitness is a must for this.
Thus, in reply to your query, I would say that there is no such thing as times that you can appear in the NDA exam.