Design a Content Delivery Network (CDN)

Build a globally distributed caching system that delivers static content with low latency from edge locations.

Functional Requirements

• Cache and serve static assets (images, videos, scripts)
• Route users to the nearest edge location
• Invalidate cached content on demand
• Support for custom caching rules and headers
• Real-time analytics and logging
• DDoS protection and WAF integration

Non-Functional Requirements

• Sub-50ms latency globally
• 99.99% availability
• Handle millions of requests per second
• Efficient cache hit ratios (>95%)

Questions to Consider

• How do you route users to the optimal edge server?
• What cache invalidation strategy will you use?
• How do you handle cache misses efficiently?