Availability Zone
One or more discrete datacenters within a Region, each with independent power and networking.
An Availability Zone (AZ) is one or more discrete data centers within an AWS Region, each with independent power, cooling, and networking. AZs in a Region are connected by high-bandwidth, low-latency private fiber, enabling replication and failover without cross-Region traffic costs. The key exam distinction: a Region is a geographic area containing multiple AZs (new Regions launch with at least three), while an AZ is the fault-isolation boundary inside it. Services like Amazon EC2 and RDS deploy at the AZ level, so spreading instances across multiple AZs is the standard high-availability pattern.
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