Subnets

Private

You should place as many of your resources as possible into private subnets. This ensures that your resources are not publicly accessible, greatly reducing the attack surface. Resources that should be placed in private subnets include:

• Elastic Compute (EC2) instances
• Elastic Container Service (ECS) cluster
• Relational Database Service (RDS) database
• Elastic File System (EFS) volumes

Public

Amazon defines public subnets as subnets having a route table that directs traffic to an internet gateway. You will need to create a route table with a route to the internet gateway, then associate your public subnets to that route table.

There are some resources that must be placed in a public subnet. For instance, the load balancer needs to accept requests from the internet and route them to Mirth® Connect by NextGen Healthcare running in a private subnet. Resources in public subnets include:

• Load Balancers
• NAT Gateways