Amazon EC2 is hosted in multiple locations worldwide, and these locations are composed of regions and availability zones. Each region is a separate geographic area and has multiple, isolated locations known as availability zones. When launching an instance, you can use the EC2 VPC Console to create a new subnet or select No preference to allow AWS to select the best subnet in any availability zone. Teradata recommends using subnets especially if you want to launch Teradata Database MPP instances. You must enable auto-assignment of public IP addresses for subnets before launching software.