An enterprise is designing a mission-critical workload on Azure Virtual Machines and needs to maximize reliability. The solution must satisfy the following architectural requirements: Provide resilience and continuous operation even if an entire datacenter facility experiences a power, cooling, or networking failure Deploy redundant VM instances across distinct physical locations within the same Azure region Maintain low-latency connectivity between the redundant application instances Which Azure reliability feature should the enterprise implement to meet these requirements?

Availability zones: ### What Availability Zones Are **Azure Availability Zones** are physically separate locations within an Azure region. Each availability zone is made up of one or more distinct datacenters equipped with independent power, cooling, and networking infrastructure. Azure regions that support availability zones feature a minimum of three separate zones to ensure high resilience and fault tolerance. ### How It Meets the Requirements - **Resilience against datacenter failure:** Because each availability zone has dedicated power, cooling, and network links, a complete outage at one physical datacenter does not affect the operation of workloads deployed in the other zones. - **Distinct physical locations within a region:** Availability zones allow virtual machines and storage resources to be distributed across separate physical facilities while remaining within the same geographic region boundary. - **Low-latency performance:** Zones within an Azure region are interconnected via a high-speed, low-latency private fiber network, allowing synchronous replication and rapid inter-zone communication. ### Key Advantages and Capabilities - **Fault isolation:** Isolates hardware, software, and facility-level failures to a single physical zone. - **High availability SLAs:** Delivers industry-leading uptime service-level agreements (SLAs) for virtual machines distributed across zones. - **Automated traffic rerouting:** Integrates with Azure load balancers and services to automatically direct traffic away from unhealthy zones to healthy instances. - **Zone-redundant storage:** Supports zone-redundant storage (ZRS) to replicate data across three availability zones automatically. ### Why This Is Optimal Deploying across **Availability Zones** is the optimal design choice because it provides isolation from catastrophic facility-level disruptions without requiring cross-region disaster recovery replication overhead.