> There is a whole industry and providers around switching CDN's in real
> time. Web-search "Cdn switch" will find them, for example.
What do you mean by "in real-time"?
I don't know what those other products consider, but I know five seconds happens.
> It also works for multiple CDNs, provided they don't keep switching back
and forth, or proving some modest set of trust-anchors is known to cover
them all.
The CDN's are generally part of the WebPKI because browsers connect to them.
> And do they keep switching back and forth, or is a one time switch
stable for some days or longer?
I've seen both short-term shifts (an hour or two), and long-term shifts (measured in days).
I am sorry I cannot provide specifics, naming our customers for example.
