Hello,
To join DRDO you have to appear for DRDO-SET.

Eligibility Criteria :-

1) Education :- You have to get at least first class in BE/B.Tech in the streams Chemical Engg/ Mechanical Engg /Electronics & Communication Engg / Computer Science & Engg/ Electrical Engg from a recognized
University.

2) Age Limit :- 28 years

3) Nationality :- Only Indian can apply.

Candidates appearing in the final examination (final semester) may also apply.

Exam Pattern of DRDO-SET :-
Questions consist of two sections -
1) Section A:- 100 questions to test your knowledge in the technical.

2) Section B:- 50 questions to test your aptitude relevant to Applied Research & Development.

Forms generally available in December every year.

For more details please visit this link
here

Hope it helps

Hello aspirant,
I am here for helping you...
You didn't explain your question clearly so that we could answer you but still we are providing you some data by which you can have idea about DRDO.
You can have complete knowledge about this by going through the below link:
https://engineering.careers360.com/articles/isro-drdo-barc-dae-how-work-here/amp
I hope it will be beneficial for you....
For more queries you can  upvote my answer and can ask in the comment section below...

Best of luck...