Before 2013, AWS supported EC2-Classic. All AWS accounts created after December 4, 2013 only support EC2-VPC. If an AWS account only supports EC2-VPC, then a default VPC is created in each region and a default subnet in each AZ. Default subnets are public in nature. To meet enterprise requirements, it is possible to create a custom VPC and subnet. This custom VPC and subnet can have a custom CIDR range and can also decide which subnet can be public and which one can be private. When an AWS account only supports EC2-VPC and it has no custom VPC created, then Amazon RDS DB instances are created inside a default VPC.
Amazon RDS DB instances can also be launched into a custom VPC just like EC2 instances. Amazon RDS DB instances have the same functionality in terms of performance, maintenance, upgrading, recovery, and failover detection capability, irrespective of...
