Your question is Ticket Booking at Massive Scale. Take a moment with it on the right.
Talk me through your thinking if you like. When you're confident, submit your answer and I'll grade it like a real screen (7/10 or better passes).
Describe how you would design a ticket booking system that can handle billions of records, including how you would handle distributed transactions.
Clarify the booking lifecycle, inventory consistency requirements, and failure guarantees before proposing the architecture. Address where ML could safely assist with demand forecasting, fraud or bot detection, or ranking available events without compromising transactional correctness. Cover scale assumptions, online and batch processing, observability, and recovery from partial failures.