AWS ECS Cluster - Instances

I have a "Custom VPC" with two subnets (A private subnet & a public subnet).

In ECS, when I try and create a cluster with "Custom VPC" and both subnets selected. The EC2 instances launched, are by default launched in the private subnets.

  1. Why?, Is there a way to change the instance subnet after it is launched?
  2. Should ECS cluster only have public subnets of a VPC? and launch an instance on the private subnet through the 'Launch instance' wizard?
  3. Also, these instances have a public DNS even when the private subnet 'auto assign public IP' is disabled. Why?

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