What is a content delivery network (CDN)?

CDN: definition

Without a CDN, every file comes from the website's origin server, regardless of whether the visitor is in Speyer or São Paulo. A CDN stores copies of these files on many so-called edge servers in different regions. The visitor receives the data from the nearest location.

Well-known providers include Cloudflare, Akamai, Fastly, Amazon CloudFront, and the European provider Bunny.net. Many hosting and e-commerce platforms already have a CDN built in, so it only needs to be activated and configured.

How a CDN works

When a visitor requests a file, the nearest edge server checks whether it has an up-to-date copy. If it does, it delivers it immediately. If not, it fetches it once from the origin server and stores it for further requests. Cache rules control how long content remains valid.

Modern CDNs can do more than caching. Typical additional features include:

• Automatic image optimization and compression
• Protection against DDoS attacks and a web application firewall (WAF)
• TLS encryption directly at the edge server
• Targeted cache purging after content changes

Benefits and limitations of a CDN

Shorter distances mean shorter loading times. This improves the user experience and has a positive effect on metrics such as Core Web Vitals. Because fewer requests reach your own server, the website remains stable even during traffic spikes.

However, a CDN is no substitute for a well-optimized website: slow database queries or bloated pages won't get any faster because of it. For personalized content such as the shopping cart or customer account, you need to define precisely what may be cached. In addition, IP addresses are transmitted to the provider, which needs to be assessed under data protection law.

• Faster loading times, especially for distant visitors
• Less load on the origin server
• Additional protection against attacks
• Define cache rules and data protection carefully

Real-world example: a CDN for an online store

An online store with many product images also sells to Austria and Switzerland. The images are delivered via a CDN and automatically converted to modern formats such as WebP along the way. The pages load noticeably faster, and promotional days with many visitors no longer push the server to its limits.

A CDN pays off for websites with lots of media, visitors from beyond the region, or fluctuating load. Nano Concepts sets up CDNs, defines suitable cache rules, and combines the setup with loading time optimization.