AWS Secrets Manager is a regional service that is accessed through private AWS endpoints. In a VPC without internet access, AWS recommends using AWS PrivateLink through interface VPC endpoints to enable secure, private connectivity to supported AWS services. According to AWS Certified Security – Specialty documentation, interface VPC endpoints allow resources within a VPC to communicate with AWS services without traversing the public internet, NAT devices, or internet gateways.

An interface VPC endpoint for Secrets Manager creates elastic network interfaces (ENIs) within the VPC subnets and assigns private IP addresses that route traffic directly to the Secrets Manager service. Because the VPC has private DNS enabled, the standard Secrets Manager DNS hostname resolves to the private IP addresses of the interface endpoint, allowing the Lambda rotation function to communicate securely and transparently.

Option A introduces unnecessary complexity and expands the attack surface by allowing outbound internet access. Option B is incorrect because gateway VPC endpoints are supported only for Amazon S3 and Amazon DynamoDB. Option D violates the security requirement by exposing the VPC to the internet.

AWS security best practices explicitly recommend interface VPC endpoints as the most secure connectivity method for private VPC workloads accessing AWS managed services.

Referenced AWS Specialty Documents:

AWS Certified Security – Specialty Official Study Guide

AWS Secrets Manager Security Architecture

AWS PrivateLink and Interface VPC Endpoints Documentation