A company has a hybrid environment in which a VPC connects to an on-premises network through an AWS Site-to-Site VPN connection. The VPC contains an application that is hosted on Amazon EC2…

Using an internet gateway would expose DynamoDB traffic to the public internet, which is less secure, and private subnet instances cannot directly use an internet gateway for outbound connections without a NAT device. The ALB is for inbound traffic to EC2, not outbound from EC2.

While a NAT Gateway enables outbound internet access for private instances, accessing DynamoDB via its public endpoint through a NAT Gateway is not as secure or private as using a VPC endpoint, as the traffic would still be routed publicly within the AWS network.

Routing DynamoDB traffic (an AWS service) through an on-premises network via a Site-to-Site VPN is an inefficient and impractical approach, introducing unnecessary latency and complexity.

Creating a Gateway VPC endpoint for DynamoDB allows EC2 instances in private subnets to access DynamoDB directly and securely without traversing the public internet or requiring a NAT Gateway. This private connection is achieved by adding an entry to the private subnet's route table that directs all traffic destined for DynamoDB through the VPC endpoint, keeping the traffic within the Amazon network.