CDN
NetworkingCDN is a distributed network of servers that caches and delivers website content from locations closer to visitors. By serving static files and sometimes dynamic content through edge nodes, a CDN reduces latency, improves load times, and helps absorb traffic spikes. It also adds resilience by routing around outages and can provide security features like DDoS mitigation and TLS termination.
How It Works
A CDN places copies of your site assets (such as images, CSS, JavaScript, fonts, and downloadable files) on edge servers in many geographic regions. When a visitor requests a page, DNS or anycast routing directs that request to a nearby edge location. The edge server responds from cache when possible, reducing the distance data must travel and lowering round-trip time compared with fetching everything from the origin web server.
Caching behavior is controlled by HTTP headers (Cache-Control, Expires) and CDN rules. Assets are stored for a defined time-to-live (TTL) and refreshed when they expire or when you purge the cache after a deployment. Many CDNs also proxy requests to the origin for uncached content, support compression (gzip or Brotli), HTTP/2 and HTTP/3, TLS termination, and Web Application Firewall (WAF) policies. Some setups use a pull model (CDN fetches from origin on demand), while others use a push model (you upload assets to the CDN).
Why It Matters for Web Hosting
CDNs change what you need from a hosting plan by offloading bandwidth and request volume from the origin server, which can let smaller plans handle more visitors and improve global performance. When comparing hosts, consider how well the platform supports CDN integration (easy DNS changes, TLS, caching headers, and purge tools), whether the origin has enough CPU and I/O for cache misses, and how the provider handles real client IPs and logs behind a reverse proxy.
Common Use Cases
- Speeding up global delivery of static assets (images, CSS, JS)
- Reducing origin bandwidth and smoothing traffic spikes during campaigns or launches
- Improving availability by serving cached pages during partial origin outages
- Adding security layers such as DDoS protection, rate limiting, and WAF rules
- Optimizing media delivery (image resizing, video segment caching) at the edge
CDN vs Reverse Proxy
A CDN is a geographically distributed reverse proxy focused on caching and delivering content from edge locations close to users. A reverse proxy is a broader pattern that sits in front of an origin to route traffic, terminate TLS, and apply policies, often within a single data center or region. In hosting, you might use both: a CDN at the edge for global acceleration and a local reverse proxy (for example, Nginx) for load balancing and application routing at the origin.