DRDO stands for Defense Research & Development Organization. The institute does defense development regarding national security and war fare purposes. Defense research organization usually doesn't R&D on Missiles, Drones or survilience technology etc.

Now for getting into DRDO you can go for multiple number of subjects starting from Engineering to Psychology.

Some of the popular subject of recruitment in DRDO are:

• Physics
• Chemistry
• Mathematics
• Psychology
• Engineering

So depending on your interest you can choose the field. For engineering in most of the cases the need is for BTech but for some posts it may need a MTech. For other subjects MSc is must.

The selection is via GATE examination. You have to qualify GATE paper corresponding to your subject. If you can get very good marks then you will be called for Interview. Also DRDO conducts examination by qualifying which you can get a job.

This answer have provided some sort of idea. If you have more questions feel free to ask.

To know more about GATE visit the link below:

https://engineering.careers360.com/articles/gate

To know more about recruitment at DRDO visit the link below:

https://engineering.careers360.com/articles/drdo-recruitment-through-gate

I hope this answer helps. All the very best for your future endeavors!