An application runs on an Elastic Compute Service (ECS) with an Elastic IP address in...

VPC peering provides direct private communication between two VPCs without exposing either application or database traffic to the public Internet. Alibaba Cloud VPCs are isolated by default. After creating a peering connection and configuring the required bidirectional routes, resources in VPC A and VPC B can communicate using private IP addresses. VPC peering supports same-account and cross-account connections as well as same-region and cross-region configurations.

This is materially more secure than exposing the database publicly. The application ' s existing EIP does not need to participate in database connectivity; the application can use its ECS private address when communicating across the peering link. Security-group and database whitelist rules should then restrict access to only the required source CIDRs and ports.

Option A intentionally routes database access through public addressing. Option B introduces an unnecessary proxy server, additional management overhead, and another failure point. Option D creates the largest attack surface by making the database Internet-accessible.

The design principle is straightforward: when workloads in two Alibaba Cloud VPCs require direct communication, establish private network connectivity and keep sensitive database traffic off the Internet.

Study Guide reference: Building Enterprise-grade Networks on Alibaba Cloud — VPC isolation, VPC peering, routing, and private database access.