ContentDeliveryNetzwerk

ContentDeliveryNetzwerk, or CDN, is a distributed network of servers and data centers that cache and deliver web content to users from locations near them. The main purpose is to improve performance, reliability and scalability by reducing latency and bandwidth usage on the origin server.

Operation: Edge servers store copies of static assets such as images, CSS and JavaScript, and sometimes optimize or transcode media. When a user requests content, the request is routed to the nearest edge node by DNS-based routing or Anycast. If the asset is cached, it is served directly; otherwise it is fetched from the origin and cached for future requests. CDNs support caching policies via cache-control headers and expiration times, and many also accelerate dynamic content through special routing and optimization. Modern CDNs use protocols like HTTP/2 and HTTP/3 and provide TLS termination at the edge.

Benefits and security: CDNs reduce page load times, increase throughput, and protect against traffic spikes and server outages. They often include security features such as DDoS protection, Web Application Firewall, TLS termination, bot mitigation and hotlink protection. Typical use cases include video and software delivery, e-commerce, large media sites, and mobile apps. Deployment considerations include cache policy management, data privacy and jurisdiction, integration with origin infrastructure, and monitoring of performance and costs.

History and providers: The CDN concept emerged in the 1990s with early networks such as Akamai. Since then, numerous providers have built global edge networks, including Cloudflare, AWS CloudFront, Fastly, and Microsoft Azure CDN, along with regional players and private deployments.