System design interview question
Design a Multi-Region Distributed Cache Invalidation System for a Global CDN Edge Network
Design a cache invalidation and consistency system for a global Content Delivery Network serving 500M+ users across 6 continents. The system must handle invalidation requests for 50K URLs/second during peak traffic, propagate invalidation signals to 10K+ edge nodes within sub-second latency, and maintain strong consistency guarantees for critical content (e.g., real-time pricing, user profiles) while allowing eventual consistency for non-critical content. The system must tolerate network partitions between regions, handle Byzantine failures in edge nodes, and support batch and real-time invalidation patterns without impacting origin server load or end-user latency.
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