General Aptitude questions, (Quant, DI-LR and Verbal). Practice Indiabix to solve such type of questions.

This was a PSDD round in which a case study was given and based on that case there were 7-8 multiple choice questions. For preparation refer Case Interviews Cracked.

In this round general HR questions asked along with one or two guesstimates in the end. 15 seconds of time is given to structure your thoughts and max 3 mins of time is given to record the answer. I was asked a guesstimate of the total no of cabs that travel to and fro from the Delhi International Airport in a month.
To clear this round good communication skills are required and most of the people are eliminated in this round.

After you clear the above three rounds, you will receive a mail from the HR after 2-3 weeks for the case study round. You will be given a case which will have lots of graphs and data tables. Based on these there are 3 Parts. Each Part has 3-4 questions which have quantitative as well as subjective answers. Time management is very important in this round. Even if you are not able to get to the final answer try to formulate an approach.
The case can be related to pricing, market entry, P and L or Sales force optimization.
You will have to upload your solutions on the Talview platform in PDF format.

This round is the case discussion round where you will have to discuss the solutions of the case with the interviewer. You may also be asked some guesstimates as well as puzzles in the end.
I was asked a Guesstimate which was related to the no of tennis balls in play at any given instance. Try to cross check the final answer from the supply as well as demand side while solving guesstimates. I solved the guesstimate partially and didn't think of the supply side but still managed to clear this round.

This round of interview was taken by one of the senior managers of ZS. Below are the questions that were asked.
1) Tell me about yourself
2) Why ZS
3) Why Decision Analytics
4) Why changing job just after a couple of months
5) Explain any one of the project in your resume
6) 2 Puzzles - Ant triangle puzzle and simple puzzle based on pnc
Don't take this round lightly and be confident with your answers!

It is one of the best companies to start your career with and it provides an exponential learning curve right from the beginning! Moreover the culture is very good at ZS!