Oracle Internship interview questions

This was a campus interview. The internship was in Oracle Systems. First round was online test with four parts- verbal, quantitative, aptitude and basic knowledge of Computer Science(OS,SQL,etc) The next round was the interview. The interviewer was looking for people with good base in Linux and C/C++. I hadn't worked extensively with Linux before so that worked against me. The interviewer asked me questions in OS which I answered; also asked me to code solutions to simple problems. The interviewer also asked me to explain all the projects I had taken part in (from my CV) and quizzed me extensively on what work I had done and what I had learnt (networking concepts, RTOS concepts) all of which I answered correctly. However, I misrepresented how confident I was with Data Structures so he refrained from asking me any DS questions and sadly, my review was that my DS concepts were not good enough.