Three Data Centres and No High Availability — Why a Second Site Without a Load Balancer Is Not Redundancy
A provider with three data centres believed it had high availability. Every public request passed through one load balancer in one building. The second and third sites could not receive a single packet without it. Here is the question that exposed the gap, the four layers that all have to span sites before failover works, and the two practical ways to fix the front door — Cloudflare Load Balancing or keepalived with a virtual IP.