Which type of failure can an Azure Availability Zone protect against to maintain access to Azure services?

Azure Availability Zones are physically separate locations within an Azure region, each with independent power, cooling, and networking. This design protects against data center failures by ensuring that if one data center goes offline, applications and services running in other zones within the same region remain available. While Availability Zones can mitigate the impact of a physical server failure (as the workload can failover to another server in a different zone), their primary purpose is to provide resilience against the larger scope of an entire data center failure. They do not protect against an entire Azure region failure, as they are contained within a single region. Storage failures are a broader category that Availability Zones can help mitigate if the storage is zone-redundant, but the core protection is against the data center itself failing.