從 2020/02/19 開始，Let's Encrypt 的 ACME v1/v2 都會透過多個節點認證：「ACME v1/v2: Validating challenges from multiple network vantage points」。
從多個節點認證可以降低路由被劫持後被拿來產生 SSL Certificate 的風險，看起來會有三個機房參與，需要兩個確認：
After Feb 19th we will make four total validation requests (1 from a primary datacentre, and 3 from remote datacentres). The primary request and at least 2 of the 3 remote requests must receive the correct challenge response value for the domain to be considered authorized.
也如同標題寫的，包括了現有的 v2 與將要淘汰的 v1。