I got a call from them asking for a date I was comfortable to give the AMCAT test. I gave them a date and took the test on the said date. After 2 Months I got a call asking me if I was comfortable for 19th of July for the interview, but since I was busy that day they rescheduled it to 22nd. Case Interview - This round is all about developing a solution to a problem, they will give you some materials to study and you will have to use your problem solving skills, technical and analytical ability to come up with the solution. I was given a credit card company problem which faced a a terrible loss in the last 5 years. Behavioral Interview - This round is all about behavioral aspects and their questions will be directed towards finding out if you will be a good fit for ZS. There are some resume probing and analytical questions as well. Principal Interview - This round will is very similar to your behavioral round but there were some additional questions on technical and analytical expertise. The people are really friendly and they will do anything to make you feel comfortable. The hiring process is a bit lengthy but worth a wait. They would arrange for cabs and guesthouses if you are an out-stationed candidate.