One of my cousins was selected for both M.Tech VLSI and MS by research and had the opportunity to appear for the interview. The interview was pretty simple and they seemed to test your ability to understand and explain things.
Here are some of the questions asked by the interviewers:
General Questions
Technical Questions
After this, they enquired him about his projects.
Overall, the panelists evaluated his academic history, ability to explain things, understanding of basic concepts, and willingness to learn.