HTTP caching is probably and should be turned off when accessing a specific subd...

HTTP caching is probably and should be turned off when accessing a specific subdomain for ACME challenge (at Google reverse proxy level), I think.

One should not have to do anything extra unless the requester too also run a load balancer in front of their subdomain in question.

That’s why ACME challenge offers several different type of protocols (to get by the many caching servers.