Example. If you have a wordpress website running behind NGINX and you face an issue with spam. You would want to see the IP addresses of the users who are spamming your website. Normally, without cloudflare it is straight forward, you just look up in NGINX access log file and get the client IP addresses. But when the website is behind Cloudflare, you’ll see Cloudflare’s IP instead of user’s real IP.
The following diagram illustrates the different ways that IP addresses are handled with and without Cloudflare.