CDN

CDN stands for content delivery network, a distributed system of servers designed to deliver web content and other assets to users with high performance and reliability. By placing copies of content at many geographically dispersed edge locations, a CDN reduces the distance between the user and the content and optimizes delivery under varying network conditions. The origin server holds the canonical copy, while edge servers cache content and serve subsequent requests. Requests are directed to the most appropriate edge, using DNS-based routing, Anycast, or other load-balancing mechanisms. Caching policies, TTLs, and cache invalidation govern what content is stored or refreshed.

Typical CDN operations include serving static assets such as images, JavaScript, and style sheets; delivering media like video and software updates; and accelerating dynamic content through specialized configurations. In addition to caching, CDNs may perform content compression, image optimization, protocol enhancements (HTTP/2, HTTP/3), and edge-side computations. Security features often accompany CDN services, including DDoS mitigation, Web Application Firewalls, TLS termination, and bot protection. Some CDNs offer edge computing, real-time analytics, and programmable edge logic to run code close to users.

Benefits include lower latency, reduced bandwidth usage on the origin, improved availability during traffic spikes, and better resilience to network congestion. Limitations include potential complexity in handling highly dynamic content, cache consistency challenges, and costs that scale with data transfer and requests. The effectiveness of a CDN depends on PoP density, network peering, and geographic distribution. CDNs are widely adopted by e-commerce, media, software distribution, and gaming sectors and are provided by multiple vendors such as Akamai, Cloudflare, Amazon CloudFront, and Fastly.