Configuring Outbound Internet Access for Servers in Private Subnet

Answer D.

Since a highly available solution is required , it is advisable to use the NAT gateway option.

For more information on the differences between the NAT instance and the NAT gateway please see the below link:

To provide Internet access to instances in a private subnet of a VPC, you can use either a NAT instance or a NAT gateway. Both options allow instances in a private subnet to access the Internet while keeping them isolated from incoming traffic from the Internet. The NAT instance and the NAT gateway provide a way for instances in a private subnet to initiate outbound traffic to the Internet.

A NAT instance is an EC2 instance that you deploy in a public subnet of your VPC. The instance is configured to forward traffic from instances in a private subnet to the Internet. This solution is not highly available because it requires you to manage the EC2 instance yourself. You need to ensure that the instance is always running and that it has enough capacity to handle the traffic load.

A bastion host is an EC2 instance that is deployed in a public subnet of your VPC. You use the bastion host as a jump server to connect to instances in a private subnet. A bastion host is not a suitable solution for providing Internet access to instances in a private subnet.

A NAT gateway is a managed service that you can use to provide Internet access to instances in a private subnet. The NAT gateway is deployed in a public subnet of your VPC and is configured to forward traffic from instances in a private subnet to the Internet. The NAT gateway is highly available because it is managed by AWS and is automatically scaled to handle the traffic load.

Therefore, the correct answer to this question is D, "Use the NAT gateway service."