CDN and Edge Caching: How Distributed Networks Cut Latency by 10x

When a web application hosted on a single origin server goes viral, users in distant regions like Australia can experience latency of 300–500ms due to the physical distance data must travel. A Content Delivery Network (CDN) solves this by maintaining servers at multiple global locations, serving cached content from the node closest to the requesting user. This can reduce latency to as low as 30–50ms, roughly a tenfold improvement in response speed. CDNs are best suited for static assets such as images, CSS, JavaScript, and rarely changing API responses, while dynamic or user-specific pages like login or checkout screens should not be cached. To handle cache invalidation challenges, developers can use cache-busting techniques such as appending content hashes to file URLs, ensuring browsers and CDNs fetch updated files when content changes.