There are three rounds in the interview process (it is common irrespective of the position you have applied for)
First Round-Written Test. This includes partly technical and partly aptitude. (2 hours test)
Second Round-You are given a task based on the position you have applied. I was asked to design a COPV LOX and Kerosene tank. (4 hours)
Third Round- Team Project. The entire group is asked to "DESIGN A ROCKET" that is LIGHTER in its orbital class, CHEAPER and FASTER (4 hours)