Hi

No, you cannot appear in nda examination if you have failed in your class 12th board examination.

This is because,

In order to be eligible for NDA you must pass your class 12th.

So, if you want to appear in nda I would suggest you to again give your class 12th examination and pass it and then you will become eligible for appearing in it

For your reference,

NDA eligibility criteria is given below

NDA eligibility criteria says that:-

-------------) Qualifucation required :-

• For army :- you need educational  qualification of 10 + 2 in any stream .

• For navy and Airforce :- you need qualifucation of 10 + 2 with Physics and Maths .

  Recommended

-------------) You must be  in the age group of 16.5 to 19.5 years old to be eligible.

-------------) Earlier for nda only boys were eligible but now, girls are also eligible for Army in nda . For details on this refer:- https://news.careers360.com/nda-2021-sc-allows-women-appear-in-national-defence-academy-exam-slams-army-for-gender-discrimination

-------------) You must be unmarried.

-------------) Nationality

For details you can visit our page, the link for the same is provided below

https://competition.careers360.com/articles/nda-eligibility-criteria

Thank you