Which solution will meet these requirements MOST cost-effectively?
Create a public virtual interface (VIF). Route the AWS traffic over the public VIF.
Create a VPC and a NAT gateway. Route the AWS traffic from the on-premises network to the NAT gateway.
Create a VPC and an Amazon S3 interface endpoint. Route the AWS traffic from the on-premises network to the S3 interface endpoint.
Create a VPC peering connection between the on-premises network and Direct Connect. Route the AWS traffic over the peering connection.
Explanations:
A public virtual interface (VIF) would expose the S3 bucket to the internet, which is not suitable for a secure on-premises network with no direct internet access. This option does not ensure secure access to S3.
A NAT gateway is not needed in this scenario since the on-premises network can communicate directly with AWS services over Direct Connect without routing through the internet. This option is also more expensive due to the NAT gateway charges.
Creating a VPC with an S3 interface endpoint allows secure, private communication between the on-premises network and the S3 bucket via Direct Connect without going through the internet, making it a cost-effective and secure solution.
VPC peering is not necessary in this case, as Direct Connect already establishes a dedicated network connection between the on-premises network and AWS. This option also does not provide direct access to S3 without additional complexity and potential costs.
I calculate that the answer is:
Create a VPC and an Amazon S3 interface endpoint. Route the AWS traffic from the on-premises network to the S3 interface endpoint.