What is a CDN and how does it work?

A Content Delivery Network (CDN) is a distributed network of servers that delivers web content to users based on their geographic location. When a user requests content, the CDN routes them to the nearest edge server, reducing latency and improving load times by serving cached copies instead of fetching from the origin server.

Why do websites need a CDN?

Websites need a CDN to improve page load speeds, reduce bandwidth costs, increase content availability, and enhance security. CDNs cache content at edge locations worldwide, so users receive data from nearby servers rather than a distant origin, resulting in faster response times and better user experience.

What is the difference between a CDN and traditional web hosting?

Traditional hosting serves all requests from a single server location, while a CDN distributes content across multiple edge servers globally. This means CDN-served content loads faster for geographically distributed users, handles traffic spikes better, and provides built-in redundancy that single-server hosting cannot match.

How much does a CDN cost?

CDN costs vary widely. Free tiers from providers like Cloudflare offer basic CDN features suitable for small sites. Paid plans typically charge based on bandwidth usage, starting around $20/month for small sites and scaling to thousands for high-traffic applications. Enterprise plans offer custom pricing with SLAs and dedicated support.

When should you not use a CDN?

A CDN may not be beneficial for sites with very low traffic, purely local audiences served from a nearby data center, highly dynamic content that cannot be cached, or applications requiring real-time data consistency where cache invalidation delays are unacceptable.

CDN Fundamentals: Complete Beginner's Guide

September 25, 2026 · FlyFish NWA Editorial

Content Delivery Networks (CDNs) are the backbone of modern internet performance. This guide brings together our complete collection of CDN fundamentals — from understanding what a CDN is to deploying your first one.

Whether you're a developer, system administrator, or technical decision-maker, start here to build a solid foundation before exploring advanced topics.

What Is a CDN?Start here — understand the core concept of content delivery networks.
How CDN WorksThe request flow from user to edge server and back.
Why Websites Need a CDNPerformance, security, and reliability benefits.
CDN BenefitsDeep dive into performance and security advantages.
CDN Terminology GlossaryKey terms and definitions you'll encounter.
CDN vs Traditional HostingWhen CDN adds value vs. direct serving.
HTTP Caching FundamentalsThe caching protocols that CDNs build upon.
Free vs Paid CDNComparing free tiers with premium features.
Setting Up Your First CDNStep-by-step deployment guide.
When Not to Use a CDNCases where a CDN may not be the right choice.
CDN for Static SitesOptimizing static site delivery.

This topic cluster contains 11 articles progressing from foundational concepts to advanced implementations. Read them in order for a comprehensive understanding, or jump to any topic that interests you.

Figure 1: CDN Network Architecture — Content delivery flow from origin to edge

External References

MDN Web Docs: HTTP Caching
Cloudflare: What is a CDN
W3C Resource Timing Specification

Performance Comparison: Edge vs Origin Processing
Metric	Edge Processing	Origin Processing	Improvement
Latency (p50)	8–15 ms	120–300 ms	15–20x faster
Cache Hit Ratio	85–95%	N/A	Reduces origin load
TLS Handshake	1–5 ms (nearby PoP)	50–150 ms	10–30x faster
Bandwidth Cost	$0.01–0.04/GB	$0.05–0.12/GB	3–5x cheaper
Availability	99.99% (multi-PoP)	99.9% (single DC)	10x fewer outages

Articles in This Cluster

Continue Reading: CDN Fundamentals

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External References