The grand finale: a global real-time bidding platform

The final interview of Weeks 0 to 10: a 100 ms, 500,000 request-a-second ad auction across six continents. Requirements, estimates and a latency budget; the regional architecture and one request end to end; hierarchical budget leases that never overspend; DSP fan-out with circuit breakers and load shedding; a transactional-outbox audit trail and tiered storage; tiered fraud detection; Super Bowl scale and edge cases; SLOs and dashboards; and a send-off for ten weeks, with Week 11's AI systems next.