Hello Rananjay here on your demand I am providing you the rules to join National Defence Academy

Rules
Candidate must be citizen of India
A candidate must be an unmarried
A candidate who marries during training shall be discharged and will be liable to refund all expenditure incurred on him by the Government

Education qualification
Candidate should 12th paas conducted by a State Education Board or a University.
Candidates who are appearing in the 12th Class under the 10+2 pattern of School Education or equivalent examination can also apply.

Exam Dates (Tentative)
Notification of Examination Sept. - Oct. & May - June
Conduct of Examination March - April & Aug. - Sept.

Examination Centres
Agartala
Delhi
Kohima
Sambalpur
Ahmedabad
Dharwar
Kolkata
Shillong
Aizwal
Dispur
Lucknow
Shimla
Allahabad
Gangtok
Madurai
Srinagar
Bangalore
Hyderabad
Mumbai
Thiruvanathapuram
Bareilly
Imphal
Nagpur
Tirupati
Bhopal
Itanagar
Panaji (Goa)
Udaipur
Chandigarh
Jaipur
Patna
Vishakhapatnam
Chennai
Jammu
Port Blair
Cuttack
Jorhat
Raipur
Dehradun
Kochi
Ranchi