Which change to the network architecture should a solutions architect recommend to meet this requirement?
Create a NAT gateway. Configure the route table for the public subnets to send traffic to Amazon S3 through the NAT gateway.
Configure the security group for the EC2 instances to restrict outbound traffic so that only traffic to the S3 prefix list is permitted
Move the EC2 instances to private subnets. Create a VPC endpoint for Amazon S3, and link the endpoint to the route table for the private subnets.
Remove the internet gateway from the VPC. Set up an AWS Direct Connect connection, and route traffic to Amazon S3 over the Direct Connect connection.
Explanations:
A NAT gateway is used for enabling instances in a private subnet to access the Internet. However, since the EC2 instances are in public subnets and do not require Internet access for anything other than S3, using a NAT gateway does not fulfill the requirement of keeping S3 traffic private. Additionally, this option still routes S3 traffic over the Internet.
Restricting the outbound traffic in the security group does not ensure that the network traffic for file transfers to S3 will take a private route. Security groups operate at the instance level and do not change the underlying network routing, which would still route the traffic over the Internet.
Moving the EC2 instances to private subnets and creating a VPC endpoint for Amazon S3 allows the instances to access S3 without traversing the Internet. The VPC endpoint provides a private route for the traffic, ensuring compliance with the new requirement.
Removing the Internet gateway and setting up an AWS Direct Connect connection would not be the best approach for accessing S3, as Direct Connect is primarily used for dedicated connections to on-premises resources. Moreover, this solution does not guarantee that S3 traffic is routed privately without an Internet connection, and it adds complexity and cost without necessity for just accessing S3.
I rank that the answer is:
Move the EC2 instances to private subnets. Create a VPC endpoint for Amazon S3, and link the endpoint to the route table for the private subnets.