Hello,

The age limit to be eligible to appear for National Defence Academy entrance examination (NDA) is 16.5 years to 19.5 years. According to the above specified information you will pass 10+2 in the year 2024 if there isn't any gap in your education. The education qualification requirement to be eligible to appear for NDA is that a candidate must have passed 10+2 with Mathematics and Physics as compulsory subjects from a recognized board to get admission in Indian Naval Academy and Indian Air Force Academy and for admission in to Indian Military Academy a candidate must have passed 10+2 in any stream from a recognized board. Candidates who are appearing in the qualifying examination are also eligible to apply provided the must pass in the examination, obtain the result and certificates before attending the SSB interview at the designated SSB board if qualified in the NDA entrance examination.

You are will be 19 years on April 2, 2024. So you only have one attempt for which you are eligible to apply that is in the year 2024.