A company wants to implement their website in a virtual private cloud (VPC). The web tier will
use an Auto Scaling group across multiple Availability Zones (AZs). The database will use
Multi-AZ RDS MySQL and should not be publicly accessible. ‘What is the minimum number of
subnets that need to be configured in the VPC?
Would use VPC with private (DB) and public (WEB) subnets:
Multi AZ requirement forces me to multiply subnets by two.
For DB: Your VPC must have at least one subnet in at least two of the Availability Zones in
the region where you want to deploy your DB instance. A subnet is a segment of a VPC’s IP
address range that you can specify and that lets you group instances based on your security
and operational needs
For Web: After creating a VPC, you can add one or more subnets in each Availability Zone.
Each subnet must reside entirely within one Availability Zone and cannot span zones