An application runs on an ECS instance in a VPC.

OSS provides region-specific internal endpoints specifically for private access from Alibaba Cloud compute resources. When an ECS instance and an OSS bucket reside in the same region, the ECS instance can access the bucket using an internal OSS domain such as an oss- < region > -internal.aliyuncs.com endpoint. Traffic remains on Alibaba Cloud ' s internal network instead of traversing the public Internet.

This directly satisfies the security requirement without adding unnecessary networking components. The ECS instance does not require an EIP, NAT Gateway, or Internet connectivity for the OSS data path.

VPN Gateway is intended primarily for connecting VPCs to on-premises networks or other private networks; it is unnecessary for same-region OSS access. PrivateLink has legitimate private-service connectivity use cases, but the presence of a native OSS internal endpoint makes it unnecessary here. A VPC gateway endpoint may be relevant to certain Alibaba Cloud service integrations, but it is not required for this straightforward same-region ECS-to-OSS architecture.

The important exam design principle is to prefer a service ' s native private endpoint when one exists and the workload is already located inside the corresponding Alibaba Cloud region.

Study Guide reference: Building Enterprise-grade Networks on Alibaba Cloud — VPC private connectivity and OSS internal endpoints.