The open CA prepares for worst scenarios with new fiber, servers, cryptographic signing and more. Let s Encrypt announced an infrastructure makeover which means the open certificate authority is able to re-issue up to 200 million certificates in a 24-hour period. The upgrade comes a year after Let’s Encrypt was compromised by a Certificate Authority Authorization (CAA) bug and forced to revoke 3 million Transport Layer Security (TLS) certificates on a single day, March 4.
Source: https://threatpost.com/lets-encrypt-gears-up-to-replace-200m-certificates-a-day/164002/