What design strategy keeps an application online during datacenter-level outages within a region?

Deploying across Availability Zones is the correct strategy because Availability Zones are physically separate datacenters within an Azure region, each with independent power, cooling, and networking. This isolation ensures that if one datacenter experiences an outage (e.g., due to a natural disaster or major power failure), the application remains online by failing over to resources in another zone. Deploying multiple VMs in the same zone does not protect against datacenter-level outages, as all VMs would be affected. Local Redundant Storage (LRS) provides data durability within a single datacenter but doesn't ensure application uptime during a datacenter outage. Using a single App Service Plan offers no redundancy against regional or zonal failures.