What is CDN?
CDN is a geographically distributed network of proxy servers and data centers that work together to provide fast delivery of internet content by serving resources from locations closest to end users.
Quick Facts
| Full Name | Content Delivery Network |
|---|---|
| Created | 1998 by Akamai Technologies |
| Specification | Official Specification |
How It Works
A Content Delivery Network consists of strategically placed servers around the world that cache and deliver web content to users based on their geographic location. When a user requests content, the CDN routes the request to the nearest edge server, reducing latency and improving load times. CDNs handle various content types including static assets (images, CSS, JavaScript), video streaming, software downloads, and dynamic content. They also provide additional benefits such as DDoS protection, load balancing, SSL/TLS termination, and analytics. Major CDN providers include Cloudflare, Akamai, Amazon CloudFront, and Fastly.
Key Characteristics
- Edge servers distributed globally
- Caches content at points of presence (PoPs)
- Reduces latency through geographic proximity
- Provides redundancy and high availability
- Offloads traffic from origin servers
- Supports HTTP/2 and HTTP/3 protocols
- Offers DDoS mitigation and security features
Common Use Cases
- Static asset delivery (images, CSS, JS)
- Video and media streaming
- Software and game distribution
- E-commerce website acceleration
- API response caching
Example
Loading code...Frequently Asked Questions
How does a CDN improve website performance?
A CDN improves performance by caching content on edge servers located geographically closer to users, reducing latency. It also distributes traffic across multiple servers, preventing any single server from becoming a bottleneck. Additionally, CDNs optimize content delivery through compression and protocol optimizations.
What is the difference between origin server and edge server?
The origin server is the main server where original content is stored and managed. Edge servers are CDN servers distributed globally that cache copies of content from the origin. When users request content, edge servers serve cached content, reducing load on the origin and improving response times.
What types of content can a CDN deliver?
CDNs can deliver virtually any web content including static assets (images, CSS, JavaScript files), video and audio streaming, software downloads, API responses, and even dynamic content. Modern CDNs also handle real-time content through edge computing capabilities.
How does CDN caching work?
CDN caching stores copies of content on edge servers based on cache headers (Cache-Control, Expires). When a user requests content, the nearest edge server checks if it has a valid cached copy. If yes, it serves directly; if not, it fetches from origin, caches it, and serves to the user.
What is CDN cache invalidation?
Cache invalidation is the process of removing or updating cached content on CDN edge servers when the origin content changes. Methods include setting TTL (Time To Live), purging specific URLs, using cache tags, or implementing versioned URLs. Proper invalidation ensures users receive fresh content.