> All content delivery networks do not host content (arguable) but only effectively _relay_ content such that delivery is faster. Once the origin server goes down, so does the content. This is an integral part of how CDNs operate.

What's the point of a service that caches and accelerates errors?

If this is by design, then I don't understand most of the value proposition of CDNs. If my origin is overloaded, down, or throwing intermittent errors, I want the CDN to cover for this. But no, a CDN is just a set of mirrors for whatever you're serving now.