Amazon RDS and VPC
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, 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 whether they are launched in a VPC or not.
Amazon RDS and high availability
ELB and auto-scaling can be used with Amazon...