Hello,

Hope you are doing good.

National Defense Academy Examination is conducted for admission to the Army , Navy , Air force wings , and it doesn't depend upon the number of times you can attempt the exam rather it is the age that matters. Your age should be in between 16.5 and 19.5. So based on your date of birth you will become 19 in the year 2024. So you may appear for all NDA exams before you turn 19.5

Hope this helps