Let’s Encrypt engineer…
On Wednesday February 19th, 2020 we’ll turn on stricter validation requirements 1.7k in production. We’ll make multiple validation requests from different network perspectives. Most issuance should continue as normal; we believe that a small number of domain names may need fixing. The most common issue will be hosts that use extremely strict firewall rules to allow validation from only specified IP addresses (a practice we do not recommend 494).
t.ly/OXd8A
