I have a Microsoft Onsite this week and I need some pointers on how to crack this one. Was rejected at Amazon last month after doing avg~poor in System-Design / Behavioral. Lessons learnt - Behavioral - - do not make up things, be frank, and practice a lot using STAR method System Design - - make use of metrics before stating the architecture (latency, availability, consistency) - identify individual services needed and scale them individually as needed - do not talk about something which you cannot explain Please let me know if I am missing anything or got anything wrong or you have any other important suggestions. Thank you!