Interview Questions/System Design/Design Ad Impression & Click Tracking
AdvancedSystem-Design
45 min

Design Ad Impression & Click Tracking

StreamingFraudDataPrivacy
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Interview Question

Design an ad event pipeline for impressions, clicks, and conversions with deduplication, fraud detection, and near-real-time reporting.

Key Points to Cover
  • Event schema, idempotency keys, and late/out-of-order handling
  • Streaming ingestion (Kafka) with exactly-once processing
  • Attribution windows and join with conversion signals
  • Fraud signals: velocity, device/UA, IP reputation, bots
  • Privacy compliance and data retention/consent
Evaluation Rubric
Sound event model & dedupe strategy25% weight
Reliable streaming & joins25% weight
Effective fraud detection approach25% weight
Privacy/regulatory considerations25% weight
Hints
  • 💡Use outbox pattern to avoid missing events.
Potential Follow-up Questions
  • How to evaluate probabilistic attribution?
  • How do you combat click injection?
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