A. Subnets whose instances cannot communicate with the Internet are referred to as public subnets.
B. Subnets whose instances can communicate only with other instances in the VPC and cannot communicate directly with the Internet are referred to as private subnets.
C. All instances in the stack should have access to any package repositories that your operating system depends on, such as the Amazon Linux or Ubuntu Linux repositories.
D. Your app and custom cookbook repositories should be accessible for all instances in the stack.