CDN

A CDN (Content Delivery Network) is a globally distributed set of edge servers, organised into points of presence (PoPs), that sit between end users and an origin server. Static assets — and increasingly dynamic responses — are cached at the edge, so most requests are served close to the user instead of traversing the public internet back to the origin. The result is lower latency, lower origin bandwidth, and resilience against regional outages or traffic spikes.

Request steering is what makes a CDN work. Users are mapped to a nearby PoP using a combination of DNS-based geo/latency routing and Anycast BGP, where the same prefix is announced from every PoP and the network delivers each request to the topologically nearest one. At the edge, the PoP terminates HTTPS, applies cache rules and security policy (WAF, rate limiting, DDoS absorption), and either responds from cache or fetches from origin over a persistent backbone. Because the same IP can land on hundreds of PoPs, CDNs also absorb volumetric attacks by spreading traffic across the entire footprint rather than concentrating it on a single origin.