My IP Help

CDN

Also known as: Content Delivery Network

Content Delivery Network — a globally distributed set of caching servers that serves website assets from a location close to the end user, reducing latency and shielding the origin server.

Last updated:

What is a CDN?

A CDN (Content Delivery Network) is a fleet of geographically distributed servers that cache and serve website assets — images, JavaScript, CSS, video, API responses — from a location close to each visitor. When a user requests a page, DNS and routing steer them to the nearest CDN edge, which returns the cached copy from RAM or local disk instead of traveling across the internet to the origin server. Major CDNs include Cloudflare, Akamai, Fastly, Amazon CloudFront, and Google Cloud CDN.

How a CDN routes users

Two common steering techniques are used, often in combination:

  • DNS-based steering — the CDN's authoritative resolver returns a different IP for the same hostname based on the requester's approximate location
  • Anycast routing — the CDN announces the same IP from every POP via BGP; the internet's own routing picks the nearest one for each user

Modern CDNs also run at the application layer — terminating TLS, executing WAF rules, serving from compute workers at the edge, and shielding the origin from direct traffic.

CDN IPs in traffic analysis

CDN IPs are datacenter IPs, so any lookup on them returns the CDN's AS, not the real origin. When a visitor's source IP resolves to Cloudflare, Akamai, or Fastly, they are usually a regular user whose request was routed through the CDN; for server-to-server traffic, a CDN-origin IP can also indicate a proxy-tunneled bot. Knowing whether an IP belongs to a CDN changes how you interpret its traffic.

Identify CDN and datacenter infrastructure behind any IP with our IP lookup tool.

Frequently Asked Questions

Two ways. First, distance — by serving cached assets from a node physically close to the visitor (typically <50 ms away instead of 150-300 ms across an ocean), each request completes much faster. Second, parallelism and offload — the CDN handles the bulk of requests so the origin server never sees them, which keeps the origin fast under load. Modern CDNs also terminate TLS at the edge and pre-warm the TCP/HTTP/3 connection, saving more round-trips.
A web host runs the origin — the application code, database, and authoritative copy of every file. A CDN sits in front of the host, caches static and cacheable responses across hundreds of points of presence, and serves them from the closest one to each visitor. You still need a web host even with a CDN; the CDN just shields it from most traffic. Some platforms (Vercel, Cloudflare Workers, Netlify) blur the line by running application code at the edge itself.
Yes. Every CDN edge node sits in a datacenter (their own or a colocated facility), so any IP that resolves to a CDN's AS is by definition a datacenter IP. This matters for traffic analysis — when a visitor's source IP is a Cloudflare or Fastly address, you are usually seeing the CDN proxying a real user (the user's true IP is in `CF-Connecting-IP`, `X-Forwarded-For`, or similar), not the user themselves.
A CDN edge (or POP — Point of Presence) is a single CDN datacenter location. Major CDNs run hundreds: Cloudflare has 330+, Akamai 4,200+, Fastly 75+ as of 2025. Each edge holds a cache of recently requested content, terminates TLS, runs WAF and bot-management rules, and increasingly executes application code via "edge compute" (Cloudflare Workers, Akamai EdgeWorkers, Fastly Compute, AWS Lambda@Edge).
Not strictly, but the cost-benefit is now in their favor. Free or near-free CDN tiers from Cloudflare, Bunny, and others give global acceleration, DDoS protection, free TLS, and reduced origin bandwidth without operational overhead. The main reasons a small site might skip a CDN are when content is heavily personalized (low cache hit rate), when latency is dominated by uncacheable database queries, or when the origin is already in the same country as nearly all visitors.
Back to glossary