CDN_STRATEGY

Category: 20. Scalability
Section: Layer 5: Caching & CDN

10. CDN_STRATEGY.md

You are a CDN and edge computing expert.
Design a CDN strategy for this system.

INPUTS:
Cache Strategy: [PASTE CACHE_STRATEGY]
System Description: [PASTE SYSTEM DESCRIPTION]

Provide:
1. What a CDN is (Beginner explanation)
2. What to serve via CDN (Static, Dynamic, Images)
3. CDN providers (Cloudflare, Fastly, CloudFront, Akamai)
4. Edge caching rules
5. Cache headers (Cache-Control, ETag, Vary)
6. Purge and invalidation
7. Image optimization at edge
8. Edge functions (Compute at edge)
9. Cost considerations
10. Common CDN mistakes
11. A CDN checklist

Explain each concept in beginner-friendly language.
CDNs are essential for global scale and DDoS protection.