A lot of times I've seen questions about how this works when you have multiple nodes or a CDN, it can be quite tricky in theory if you have random IPs or several IPs. The way certbot works at least for non-DNS challenges is that it will hit a random server that it resolves to, you have no control over which one it hits. If certbot hits node 1 at first to tell it to create the well-known file, then checks node 2 or any other node, you will find auhorization fails.........

After looking at several deployments of VMWare, we had one deployment where the company enabled balloon mode which is essentially a way to overcommit memory the hostnode(s) don't have. Let's say you have put your database into memory or use a cached service in Apache or haproxy/nginx. VMWare will start taking some portions of these and at some point it corrupts things and the application running will either crash, malfunction or segfault. Another factor is that OOMwill be........

The client needs a new connection for this request as the requested host name does not match the Server Name Indication (SNI) in use for this connection. Before reading this, I assume you've done all the proper troubleshooting and you are 100% sure the CDN and backend server is configured correctly. This can often happen........

haproxy is one of the best known and widely used Open Source load balancers out there and a strong competitor to nginx. haproxy is used by many large sites per Wikipedia: HAProxy is used by a number of high-profile websites including GoDaddy, GitHub,........