Let's Encrypt does validate via multiple streams: https://letsencrypt.org/2020/02/19/multi-perspective-validation.html https://letsencrypt.org/2020/02/19/multi-

Let's Encrypt does validate via multiple streams: https://letsencrypt.org/2020/02/19/multi-perspective-validation.html https://letsencrypt.org/2020/02/19/multi-perspective-validat... But even this is vulnerable if a strong adversary can make it seem like their compromised nameserver is the only reliable nameserver reachable over the network: https://i.blackhat.com/USA21/Wednesday-Handouts/US-21-Shulman-Lets-Attack-Lets_Encrypt.pdf https://i.blackhat.com/USA21/Wednesday-Handouts/US-21-Shulma... An analysis from early 2023 indicates LE's default setup was suboptimal compared to a multi-cloud quorum policy, which seems like a no-brainer at their scale IMHO: https://arxiv.org/abs/2302.08000 https://arxiv.org/abs/2302.08000