It's in the documentation [0]. An Availability Zone is represented by a region code followed by a letter identifier; for example, us-east-1a. To ensure

It's in the documentation [0]. An Availability Zone is represented by a region code followed by a letter identifier; for example, us-east-1a. To ensure that resources are distributed across the Availability Zones for a region, we independently map Availability Zones to identifiers for each account. For example, your Availability Zone us-east-1a might not be the same location as us-east-1a for another account. There's no way for you to coordinate Availability Zones between accounts. [0] http://docs.aws.amazon.com/AWSEC2/latest/UserGuide/using-regions-availability-zones.html#concepts-regions-availability-zones http://docs.aws.amazon.com/AWSEC2/latest/UserGuide/using-reg...