Design a real-time bidding (RTB) system for online ads.
Predict, value, and bid on one impression in roughly 10ms, billions of times a day. The signal is the pCTR-to-bid pipeline under a tight latency budget, plus why calibration and budget pacing decide whether you make or lose money.
Updated Sep 2026 · Grounded in real GenAI, LLM, and AI/ML engineering interview loops and written to a senior-engineer editorial bar.
Predict, value, and bid on one impression in roughly 10ms, billions of times a day. The signal is the pCTR-to-bid pipeline under a tight latency budget, plus why calibration and budget pacing decide whether you make or lose money.
Lead with where the obvious approach breaks, because that is the judgment they are screening for — most candidates jump straight to the happy path and lose the room.
Then walk the failure back through the pipeline in order, naming the one metric the customer's exec sponsor actually cares about before you propose the fix.
