Let's Encrypt Battles Zombie Clients: A Resource Efficiency War

Let's Encrypt is battling a horde of 'zombie clients' – abandoned or misconfigured servers repeatedly requesting certificates, wasting resources. Instead of punishment, Let's Encrypt implemented a clever pausing mechanism for account-hostname pairs. After exceeding a threshold of consecutive failed validations, requests are paused, with a self-service unpause option available. Results show a significant reduction in failed requests with minimal user impact, showcasing Let's Encrypt's balance between resource management and user experience.