No my dear friend,
You can not apply for NDA because as you are the post graduate student and according to this idea your age is also be more than 21 so you are not eligible for NDA.Only the 12th class students are eligible for NDA.
NDA stands for National Defense Academy and it is the entrance exam to join any of the civil service.There are three civil services that are taken under NDA:
2.Indian Air Force
NDA is conducted by UPSC and it is held as twice in the year.You can apply for NDA after completion of 12th in any of the stream with more than 50% marks.So my friend you are not eligible for NDA.
Eligibility for NDA:
1.You must be an Indian.
2.Your age should lies between 16.5 to 19 years.
3.You must have completed your 12th with more than 50% marks.
4.You should be physically fit.
5.Your eye sight should be correct i.e.6/6.
6.Girls are not eligible for it.
7.Only unmarried males are eligible for it.