CDNs

Content delivery networks (CDNs) are distributed networks of servers designed to deliver web content to users based on their geographic location, origin, and server health. By caching static and, in some cases, dynamic content at multiple edge locations close to end users, CDNs reduce latency, increase throughput, and improve overall performance.

How a CDN works: A CDN stores copies of content at edge servers located in many points of presence around the world. When a user requests content, the request is routed to a nearby edge server via DNS-based routing or Anycast. If the edge cache holds the content, it is served directly from the edge. If not, the edge fetches it from the origin server and caches it for subsequent requests. Cache metadata and time-to-live (TTL) values control how long content remains at the edge and when it is refreshed.

Features and capabilities: Modern CDNs offer edge computing for some dynamic content, TLS termination, DDoS protection, web application firewalls, and intelligent request routing. They provide load balancing across edge nodes, real-time analytics, and mechanisms to shield the origin server from direct access.

Benefits and use cases: CDNs lower page load times, increase available bandwidth, and reduce load on origin servers. They enhance reliability and scalability for websites, APIs, software updates, multimedia streaming, and on-demand content delivery, especially for global audiences.

Industry landscape: Major providers include Akamai, Cloudflare, Amazon CloudFront, Fastly, and StackPath, among others. CDNs are offered as standalone services, integrated with cloud platforms, or deployed within enterprise networks.

Challenges: Key considerations include cache invalidation and freshness for dynamic or personalized content, cost management, privacy and regulatory compliance, and ensuring consistent performance across diverse networks.