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CDN & Network

Caching semantics, Anycast, HTTP/2 & HTTP/3/QUIC

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CDNs fundamentally change the economics of web performance. By caching content at edge locations worldwide, they reduce latency from hundreds of milliseconds to tens, decrease origin load by 85-95%, and save bandwidth costs. Modern CDNs do more than just cache—they handle TLS termination, DDoS protection, and edge computing.

The secret to CDN success is cache efficiency. Every cache miss costs you the full origin latency. Use long TTLs for static assets, implement cache busting through URL versioning, and minimize cache fragmentation from Vary headers. A well-tuned CDN can serve 95% of requests without touching your origin.

CDN & Network Performance

Caching semantics, cacheability checklist, and real-world impact of edge networks

Performance Impact
US ↔ US
60 msorigin
15 msedge
Europe ↔ US
150 msorigin
15 msedge
Asia ↔ US
300 msorigin
15 msedge
Cache hit rate 85–95% • Global coverage 200+ PoPs • 10–50× faster at edge
Popular CDN Providers
Cloudflare CDN5–15 ms (275+ cities)
AWS CloudFront10–20 ms (450+ PoPs)
Fastly CDN5–10 ms (< 150 ms purge)
Akamai5–15 ms (4000+ PoPs)
Optimization Checklist
Cache Headers
  • • Set Cache-Control max-age/s-maxage
  • • Use ETag for cache validation
  • • Prefer immutable for static assets
Best Practices
  • • Avoid Set-Cookie on cacheable responses
  • • Minimize Vary headers
  • • Use stale-while-revalidate for graceful updates

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