They given design document to prepare Interviewer was not keen on design done. But to ask question which was irrelevant when design was given for payment system. Why I will think of Fraud detection service to be applied in while adding to cart. This was in question which revolved in interview A B C D E are services A gets a payload of hotel booking info. Then it should send it to B and C, for B it will send only booking info. To C it will send hotel name and details. C will send hotel reviews and comments to D. E service will observe all these things and records each change to any of info.