Which solution should a solutions architect recommend that is MOST highly available?
Create a new public subnet with a NAT gateway in the same AZ. Distribute the traffic between the two NAT gateways.
Create an Amazon EC2 NAT instance in a new public subnet. Distribute the traffic between the NAT gateway and the NAT instance.
Create public subnets in each AZ and launch a NAT gateway in each subnet. Configure the traffic from the private subnets in each AZ to the respective NAT gateway.
Create an Amazon EC2 NAT instance in the same public subnet. Replace the NAT gateway with the NAT instance and associate the instance with an Auto Scaling group with an appropriate scaling policy.
Explanations:
Creating a new public subnet with a NAT gateway in the same AZ does not provide high availability since both NAT gateways would be in the same AZ.
Using a NAT instance alongside a NAT gateway does not ensure high availability, as both could still fail if they’re in the same AZ.
Creating public subnets in each AZ with a NAT gateway in each ensures that instances in private subnets have access to their local NAT gateway, providing high availability in case one AZ fails.
Using a NAT instance in the same public subnet and relying on an Auto Scaling group does not guarantee high availability across multiple AZs.
I calculate that the answer is:
Create public subnets in each AZ and launch a NAT gateway in each subnet. Configure the traffic from the private subnets in each AZ to the respective NAT gateway.