Hi Raman,

It seems you are already pursuing Btech in Aerospace engineering as of now. See most of the deemed companies or institutions that offer job in this department are PSUs like the one you mentioned DRDO. Usually the criteria for job there includes passing the job interview and they often ask for the GATE score. That is the evaluation criteria for them. So my advice to you would be if you want to pursue a career in DRDO you should definitely take GATE.

Good Luck !!