Introduction to a CDN

A content delivery network (CDN) is a distributed system of servers placed in many geographic locations to improve the speed and reliability of delivering online content. Rather than relying on a single origin server that holds the original version of the data, a CDN uses a network of proxy servers positioned closer to users. When requests arrive, these nearby servers act as intermediaries, providing content on behalf of the origin server. This setup reduces the load on the origin server and helps protect it from traffic spikes and potential attacks.

The proxy servers are placed at the network edgeThe network edge is the zone where a device or local network interfaces with the Internet. and are often called edge servers. By storing copies of content near end users, edge servers reduce latency, save bandwidth, and deliver data more quickly. A basic proxy simply forwards requests, but a CDN adds intelligence that optimizes how and where content is delivered.

The guiding idea behind a CDN is to minimize the distance that data must travel to reach the user. To achieve this, CDNs place small data centers near users and store copies of the required content there. By storing both staticThis type of data doesn’t change frequently and remains on the servers for a long period. and dynamicThis type of data changes most frequently—for example, newsletters, ads, live videos, and so on. content close to end users, CDNs can ...