Which solution will meet these requirements with the LEAST administrative overhead?
Create a peering connection between the VPCs. Create a VPN connection between the VPCs and the on-premises locations.
Launch an Amazon EC2 instance. On the instance, include VPN software that uses a VPN connection to connect all VPCs and on-premises locations.
Create a transit gateway. Create VPC attachments for the VPC connections. Create VPN attachments for the on-premises connections.
Create an AWS Direct Connect connection between the on-premises locations and a central VPC. Connect the central VPC to other VPCs by using peering connections.
Explanations:
Creating a peering connection between VPCs and a VPN connection to on-premises locations can work but introduces complexity as the number of VPCs increases. Each new VPC would require individual peering connections, leading to a management overhead.
Launching an EC2 instance to handle VPN connections adds unnecessary complexity and administrative overhead. It requires maintaining the instance, configuring VPN software, and scaling it as the number of VPCs increases, which is not efficient or scalable.
Creating a transit gateway simplifies the management of multiple VPCs and on-premises connections. It allows for scalable and efficient routing between multiple VPCs and on-premises locations, reducing administrative overhead as new connections are added.
Using AWS Direct Connect for a central VPC and peering it with other VPCs introduces a management challenge with peering connections. Additionally, Direct Connect is more complex and costly compared to VPN and does not simplify the overall administration as effectively as a transit gateway would.
Based on what I know, the answer is:
Create a transit gateway. Create VPC attachments for the VPC connections. Create VPN attachments for the on-premises connections.