NDA stands for National Defence Academy, it is a joint military academy for the Indian Army, Navy and Air Force. The NDA exam is conducted twice a year by the Union Public Service Commission (UPSC) for admission to the Army, Navy and Air Force wings of the NDA and Indian Naval Academy Course (INAC).

The NDA exam consists of two papers: Maths and General Ability Test (GAT). The Maths paper tests the candidate’s knowledge of algebra, trigonometry, geometry, and calculus, while the GAT tests English, general knowledge, and general mental ability. Candidates who pass the written exam are then called for an interview process known as the Services Selection Board (SSB) interview.

The eligibility criteria for appearing in the NDA Exam are:

• Only unmarried male candidates are eligible to apply
• The candidate must have passed 10+2 or equivalent examination from a recognized Board or University
• The candidate must be at least 16.5 years old and not older than 19.5 years on the first day of the month in which the course is due to commence.

Candidates are selected on the basis of their performance in the written examination and the SSB interview.