How Cloudflare works
Fundamentally, Cloudflare is a large network of servers that can improve the security, performance, and reliability of anything connected to the Internet.
Cloudflare does this by serving as a reverse proxy for your web traffic. All requests to and from your origin flow through Cloudflare and — as these requests pass through our network — we can apply various rules and optimizations to improve security, performance, and reliability.
Life of a request
Even though it feels pretty instantaneous, there’s a lot happening when you type www.example.com into your browser.
A website’s content does not technically live at a URL like www.example.com, but rather at an IP address like 192.0.2.1. It’s similar to how we say that Cloudflare’s headquarters is 101 Townsend St., San Francisco, CA 94107, but really that address is just a placeholder for latitude and longitude coordinates (37.780259, -122.390519). URLs and street addresses are much easier for humans to remember.
The process of converting a human-readable URL (www.example.com) into a machine-friendly address (192.0.2.1) is known as a DNS lookup.
Without Cloudflare
Without Cloudflare, DNS lookups for your application’s URL return the IP address of your origin server.
| URL | Returned IP address |
|---|---|
example.com | 192.0.2.1 |
When using Cloudflare with unproxied DNS records, DNS lookups for unproxied domains or subdomains also return your origin’s IP address.
Another way of thinking about this concept is that visitors directly connect with your origin server.
With Cloudflare
With Cloudflare — meaning your domain or subdomain is using proxied DNS records — DNS lookups for your application’s URL will resolve to Cloudflare Anycast IPs instead of their original DNS target.
| URL | Returned IP address |
|---|---|
example.com | 104.16.77.250 |
This means that all requests intended for proxied hostnames will go to Cloudflare first and then be forwarded to your origin server.
Cloudflare assigns specific Anycast IPs to your domain dynamically and these IPs may change at any time. This is an expected part of the operation of our Anycast network and does not affect the proxy behavior described above.
Benefits
When your traffic is proxied through Cloudflare before reaching your origin server, your application gets additional security, performance, and reliability benefits.
Security
Beyond hiding your origin’s IP address from potential attackers, Cloudflare also stops malicious traffic before it reaches your origin web server.
Cloudflare automatically mitigates security risks using our WAF and DDoS protection.
For additional details on security, refer to our guide on how to Secure your website.
Performance
For proxied traffic, Cloudflare also serves as a Content Delivery Network (CDN), caching static resources and otherwise optimizing asset delivery.
For additional details on performance, refer to our guides on Optimizing Site Speed and Caching.
Reliability
Cloudflare’s globally distributed Anycast network routes visitor requests to the nearest Cloudflare data center.
Combined together with our CDN and DDoS protection, our network helps keep your application online.