What Actually Happens When You Put a CDN in Front of Your Website?
If you've worked on web performance for any amount of time, you've probably heard the advice: “Put it behind a CDN.” But what does a CDN actually do between the browser and your server? The simplest way I think about it is this: A CDN, or Content Delivery Network, is a distributed network of edge servers that delivers content from locations closer to users instead of sending every request back to…
When you introduce a Content Delivery Network (CDN) in front of your website, it creates a distributed network of edge servers that deliver content from locations closer to users. This reduces latency, speeds up content delivery, alleviates the load on the origin server, and enhances application resilience during traffic spikes.
Without a CDN, a user in Singapore accessing your website hosted on a US-based origin server must travel the full distance between them and your server, resulting in increased network hops and round trips, which add to latency. With a CDN in place, the user is directed to a nearby CDN edge server. The CDN checks if the requested content is already cached at this edge location.
If it is (a cache hit), the CDN sends the content directly to the user without involving the origin server. If not (a cache miss), the CDN fetches the content from the origin, returns it to the user, and stores a copy for future requests.
The effectiveness of a CDN depends on several factors. The Time to Live (TTL) setting determines how long a cached resource can remain valid at the edge before it expires. Longer TTLs are suitable for rarely changing assets like logos or versioned files, while shorter TTLs are better for frequently changing resources. Immediate removal of cached content is possible via the CDN's purge mechanism.
CDNs are beneficial for applications that serve large assets like images, video, JavaScript, or have high volumes of repeat requests, especially when users are geographically dispersed. They also contribute to an application's reliability and security by helping with traffic distribution, origin protection, DDoS mitigation, and web application security.
However, it is essential to remember that CDNs complement your web hosting infrastructure, not replace it. They work by optimizing the content delivery process, not by running the original application or hosting the files.
Written by urgent.news from Dev.to's reporting — not their text. Machine-written — it may contain errors, so check the original before relying on it.
