How can I know if a resource is being served through a CDN?

This is the situation...

• I am currently working on a site that just started with Cloudflare.
• I don´t have access to cloudflare
• There are some performance issues due to animated gifs
• I want to check whether or not these resources are being served through Cloudflare

I know I can check this by going to Chrome inspector, searching the resource´s header but, beyond this, I don´t know what I need to check in order to know that resource is being served through the CDN.

Thoughts?

If the site is on CloudFlare, then the images are most likely hosted via CloudFlare. It really comes down to the domain name.

Say your website is at example.com and the image you're trying to detect is at example.com/wp-content/uploads/image.jpg then it is also going through CF. If your website is at a different subdomain (e.g. cdn.example.com) then it might be a different CDN like Amazon S3. Ultimately, here's how to detect.


Below are instructions on how to get whois info to check for CloudFlare or other CDN
Take your url and get the domain by itself
cdn.example.com or example.com

Get the IP of that domain. If you have windows, just go to cmd and run
ping example.com

It should give you an IP like 123.45.67.89

And do a whois at https://who.is/ and it'll tell you if that IP comes from CloudFlare.

Here's an example of a CloudFlare IP
https://who.is/whois-ip/ip-address/104.20.100.135