Hi Aditya!

You can write NDA 1, NDA 2 this year 2021, 2022 (NDA1 and 2), 2023 (NDA 1). As per  the eligibility criteria, you can give first attempt when you are 15 years and 10 months old. On an average, every NDA aspirant gets minimum 4 attempts for NDA exam (if he gives his first attempt in 12th standard) So, number of attempts may vary from aspirant to aspirant. To know more, visit here:

NDA Eligibility Criteria 2022 - Age Limit, Qualification, Nationality, Attempt Limit (careers360.com)

Thankyou!