Region and AZ

A region and availability zone (AZ) identify the location of a data center. You can create resources in a specific region and AZ.

• A region is a physical data center. Each region is completely independent, improving fault tolerance and stability. After a resource is created, its region cannot be changed.
• An AZ is a physical location using independent power supplies and networks. Faults in an AZ do not affect other AZs. A region can contain multiple AZs, which are physically isolated but interconnected through internal networks. This ensures the independence of AZs and provides low-cost and low-latency network connections.

Figure 1 shows the relationship between regions and AZs.

You are advised to select a region close to you or your target users. This reduces network latency and improves access speed.

When determining whether to deploy resources in the same AZ, consider your applications' requirements for disaster recovery (DR) and network latency.

• For high DR capability, deploy resources in different AZs in the same region.
• For low network latency, deploy resources in the same AZ.

Before using an API to call resources, you must specify its region and endpoint. For details about regions and endpoints, see Regions and Endpoints.