Glossary
CDN
Content Delivery Network
What is a CDN?
A CDN (Content Delivery Network) is a network of servers spread across many geographic locations that work together to deliver web content quickly. Instead of every visitor fetching images, scripts, and stylesheets from one origin server, the CDN serves cached copies from an "edge" server close to the visitor.
Shorter physical distance means lower latency, so pages load noticeably faster - especially for visitors far from your hosting location. CDNs also absorb traffic spikes and many types of attack traffic, reducing the load on your origin server and keeping your site online during busy periods.
How a CDN Works
- Caching - Static files (images, CSS, JavaScript) are copied to edge servers worldwide
- Routing - DNS directs each visitor to the nearest or fastest edge server
- Cache rules - Headers and TTLs control how long content stays cached before refreshing
- Origin shield - Only cache misses reach your actual web server, cutting its workload
- Security layer - Many CDNs include DDoS protection, a firewall, and free SSL/TLS certificates
CDNs in Practice
- Popular providers - Cloudflare, Fastly, Amazon CloudFront, Akamai
- E-commerce - WooCommerce stores use CDNs so product images load fast for every shopper
- E-learning - Moodle sites serve video and course files through a CDN to students worldwide
- CCMS managed hosting - CDN setup and tuning is part of how CCMS keeps client WooCommerce and Moodle sites fast