A related and messier corner-case are multi-provider / multi-CDN setups.
For example, "foo.example.com" may CNAME to one of three different CDNs.
Each one of these needs to be able to manage a certificate and renew it every three months.
This likely applies to some of these other cases as well.
I don't have good answers --- ACME doesn't handle this terribly well today ---
but it is worth some thought as to how to handle.
(from Erik)
A related and messier corner-case are multi-provider / multi-CDN setups. For example, "foo.example.com" may CNAME to one of three different CDNs. Each one of these needs to be able to manage a certificate and renew it every three months. This likely applies to some of these other cases as well.
I don't have good answers --- ACME doesn't handle this terribly well today --- but it is worth some thought as to how to handle.