Availability Zone IDs for your Amazon resources - Amazon Resource Access Manager
Services or capabilities described in Amazon Web Services documentation might vary by Region. To see the differences applicable to the China Regions, see Getting Started with Amazon Web Services in China (PDF).

Availability Zone IDs for your Amazon resources

Amazon maps the physical Availability Zones randomly to the Availability Zone names for each Amazon Web Services account. This approach helps to distribute resources across the Availability Zones in an Amazon Web Services Region, instead of resources likely being concentrated in Availability Zone "a" for each Region. As a result, the Availability Zone us-east-1a for your Amazon account might not represent the same physical location as us-east-1a for a different Amazon account. For more information, see Regions and Availability Zones in the Amazon EC2 User Guide.

The following illustration shows how the AZ IDs are the same for every account even though the Availability Zone names can map differently for each account.

An illustration showing how AZ IDs are mapped differently than Availability Zone names.

For some resources, you must identify not only the Amazon Web Services Region, but also the Availability Zone. For example, an Amazon VPC subnet. Within a single account, the mapping of an Availability Zone to a specific name isn't important. But, when you use Amazon RAM to share such a resource with other Amazon Web Services accounts, the mapping is important. This random mapping complicates the ability of the account accessing the shared resource to know which Availability Zone to reference. To help with this, such resources also allow you to identify the actual location of your resources relative to your accounts by using the AZ ID. An AZ ID is a unique and consistent identifier for an Availability Zone across all Amazon Web Services accounts. For example, use1-az1 is an AZ ID for an Availability Zone in the us-east-1 Region and it represents the same physical location in every Amazon account.

You can use AZ IDs to determine the location of resources in one account relative to the resources in another account. For example, if you share a subnet in the Availability Zone with the AZ ID use1-az2 with another account, this subnet is available to that account in the Availability Zone whose AZ ID is also use1-az2. The AZ ID for each subnet is displayed in the Amazon VPC console, and can be queried using the Amazon CLI.

Console
To view the AZ IDs for the Availability Zones in your account

  1. Navigate to the Amazon RAM console page in the Amazon RAM console.

  2. You can view the AZ IDs for the current Amazon Web Services Region under Your AZ ID.

Amazon CLI
To view the AZ IDs for the Availability Zones in your account

The following example command shows the AZ IDs for the Availability Zones in the us-west-2 Region and how they are mapped for the calling Amazon Web Services account.

$ aws ec2 describe-availability-zones \
    --region us-west-2
{
    "AvailabilityZones": [
        {
            "State": "available",
            "OptInStatus": "opt-in-not-required",
            "Messages": [],
            "RegionName": "us-west-2",
            "ZoneName": "us-west-2a",
            "ZoneId": "usw2-az2",
            "GroupName": "us-west-2",
            "NetworkBorderGroup": "us-west-2",
            "ZoneType": "availability-zone"
        },
        {
            "State": "available",
            "OptInStatus": "opt-in-not-required",
            "Messages": [],
            "RegionName": "us-west-2",
            "ZoneName": "us-west-2b",
            "ZoneId": "usw2-az1",
            "GroupName": "us-west-2",
            "NetworkBorderGroup": "us-west-2",
            "ZoneType": "availability-zone"
        },
        {
            "State": "available",
            "OptInStatus": "opt-in-not-required",
            "Messages": [],
            "RegionName": "us-west-2",
            "ZoneName": "us-west-2c",
            "ZoneId": "usw2-az3",
            "GroupName": "us-west-2",
            "NetworkBorderGroup": "us-west-2",
            "ZoneType": "availability-zone"
        },
        {
            "State": "available",
            "OptInStatus": "opt-in-not-required",
            "Messages": [],
            "RegionName": "us-west-2",
            "ZoneName": "us-west-2d",
            "ZoneId": "usw2-az4",
            "GroupName": "us-west-2",
            "NetworkBorderGroup": "us-west-2",
            "ZoneType": "availability-zone"
        }
    ]
}