CDN (Content Delivery Network) 是一个由地理位置分散的服务器组成的网络,能在靠近用户的位置缓存和提供内容 — 降低延迟并减轻源服务器的负载。它是快速、全球内容交付的关键组件。
CDN 的作用
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A CDN caches content at EDGE locations (servers) around the world:
→ users get content from the NEAREST edge server (not the distant origin)
→ reduces LATENCY (shorter distance = faster) for global users
→ offloads the ORIGIN server (edges serve cached content → less origin load)
User → nearest CDN EDGE (cached? serve it) → on miss, fetch from origin, then cache
CDN 提供的内容
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✓ STATIC content → images, CSS, JS, videos, fonts, downloads (the classic use)
✓ Increasingly dynamic content, API responses (edge computing/caching)
✓ Large media (video streaming); software distribution
