The correct answer is: Use AWS Transfer Family to create an SFTP-enabled server with a public endpoint, and configure it to send uploaded files directly to the S3 data lake.

AWS Transfer Family is a fully managed service that supports SFTP, FTPS, and FTP, and can seamlessly store uploaded files in Amazon S3. It eliminates the need to provision or manage EC2 instances or custom SFTP servers, and it is designed to scale automatically and maintain high availability.

Why the other options are incorrect:

Amazon S3 File Gateway provides a way to access S3 as a file system through NFS or SMB protocols, but it does not offer an SFTP endpoint. It cannot function as a direct SFTP server, so its not compatible with the partner's protocol requirements.

Launching an EC2 instance in a private subnet with a VPN and expecting the partner to connect via VPN is overly complex, increases operational burden, and introduces potential availability issues. It also does not scale well, nor is it inherently highly available.

Setting up EC2 instances behind a Network Load Balancer with custom SFTP configurations adds significant management overhead. You are responsible for maintaining SFTP software, patching, scaling, and implementing fault tolerance. This contradicts the requirement to minimize operational overhead and ensure high availability.

Why this question is important: It tests the candidate's knowledge of fully managed AWS services that simplify secure data exchange workflows. Many exam-takers incorrectly default to EC2-based setups without realizing that AWS Transfer Family is designed exactly for this kind of use case.

Tip for similar questions: When you see keywords like 'SFTP', 'high availability', and 'minimal management', look for managed services like AWS Transfer Family that are purpose-built for secure file transfers without custom infrastructure.

Full AWS Practitioner Certification Question