Google's John Mueller confirmed that when it comes to sites that host their images (or likely other files) on an external CDN, like we do here, Google will have a separate server capacity (maybe crawl budget) for your domain versus the domain of the CDN.
Like the image above is hosted at AWS and it is not on this domain exactly, so it gets its own crawl capacity from Googlebot from the rest of the domain name.
John said on Twitter "if your images are on yoursite. somecdn .com, and your content on www. yoursite .com, we would try to track the server capacity separately for them." He said the "exception" is "if it's the same server, that doesn't change much, so we might fold it together then."
Here are those tweets:
(2/2) Will Google use our domains Crawling Budget or do all images of all customers on the CDN share the CDN domain's budget (image-cdn .com)? Or does Google treat well known CDN Domains differently?
— Benjamin Wingerter (@SEOuxIndianer) November 22, 2021
Just to be clearer, if your images are on yoursite. somecdn .com, and your content on www. yoursite .com, we would try to track the server capacity separately for them. (exception: if it's the same server, that doesn't change much, so we might fold it together then)
— 🧀 John 🧀 (@JohnMu) November 22, 2021
I don't know them, but in general, CDNs are super-easy to crawl since they're so well-tuned for serving a specific kind of content. Usually hosting static content on a CDN is a great idea.
— 🧀 John 🧀 (@JohnMu) November 22, 2021
Very good additional argument for rewriting CDN host name to our domain!
— Benjamin Wingerter (@SEOuxIndianer) November 22, 2021
Forum discussion at Twitter.