I am Abhilash Bhardwaj ( https://www.linkedin.com/in/abhilash-bhardwaj-6000b7b4/ ), last time (DRDO- Advt -136 for Scientist-B) I was one of selected students for Scientist -B position in Computer Science discipline.
I will include some of my experiences so that it can help future aspirants to crack this examination. I request you to read the entire post.
First I am including last year question papers:
DRDO CS-Paper 1 https://drive.google.com/open?id=13t9T291s2S2QCCC8qjCfBkzBCQGU3PNW
DRDO CS- Paper 2 https://drive.google.com/open?id=13sbVEMqmndQZk9Wgcvz6tPoDJCPMy3ER
Some suggestions related to Descriptive Examination:
First of all you must complete the entire gate syllabus, and don’t start with additional syllabus. Major portion consist of GATE CS syllabus except Hypervisor in OS and some other topics.
Now come to cyber security, Whatever syllabus is mentioned you can do them but last year trend reflect major element of network security like buffer overflow attacks, TCP SYN flooding attack, DNS spoofing attack, DNS Cache Poisoning, Man-in-the-middle, Ping to death attack, Denial of service attack, DDoS and many more. So focus should be given to them as well. (Soon I will try to make a consolidated list of attacks and issues.)
For Machine Learning , Last year asked questions on Simple linear regression, TF-IDF representation of Text documents, Overfitting and underfitting problems and some elements of classification problems. ML is a wide area, so you cannot cover each and everything. ( Here also I will try to make a list of topics you should read.)
Again, my request is to start with the GATE syllabus, (GATE aspirants have only solved objective questions), here we need to solve everything like semester examination in a neat and clean way. Here questions can be like building CLR tables, proving using pumping lemma, writing code for Dining Philosopher Problem, Writing assembly language programs etc. So you need to change your strategy slightly. Rather than asking how many NAND gates required for XOR, they will ask you to draw it.
For additional topics like ML and Security, interested people can contact me.
I will post my DRDO interview experience after descriptive examination.
Thanks for reading !!!