Ticket Booking and Massive Traffic

IRCTC Tatkal: A System Where 5 Million Users Try to Book Train Tickets at Exactly 10 AM

Five million users. A fixed 10 AM opening time. Only a few hundred thousand available seats. How would you design a booking system that survives this synchronized traffic spike without overselling a single berth? Explore virtual waiting rooms, randomized admission, adaptive throttling, single-writer inventory, atomic seat holds, payment recovery, bot protection, and fault-tolerant confirmation.