Question #1051
A company in the United States (US) has acquired a company in Asia. Both companies use the AWS Cloud. The US company hosts a distributed application across three VPCs in the us-west-2 Region. The application must access resources in two VPCs in the ap-northeast-1 Region but must not access any other VPCs. The VPCs in both Regions have non-overlapping CIDR ranges, and all accounts are consolidated under one organization in AWS Organizations. Which solution will meet these requirements MOST cost-effectively?
Create a transit gateway in ap-northeast-1. Attach the VPCs in us-west-2 and the two VPCs in ap-northeast-1 to the transit gateway. Configure route tables to direct traffic through the transit gateway.
Deploy a transit gateway in each Region. Attach the relevant VPCs to their regional transit gateway. Establish a peering connection between the transit gateways and update route tables to route traffic through the gateways.
Create a full mesh of VPC peering connections between all VPCs in both Regions. Update route tables to route traffic through the peering connections.
Create separate VPC peering connections from each of the three VPCs in us-west-2 to both VPCs in ap-northeast-1. Update route tables in all connected VPCs to route traffic through the peering connections.
Explanation
Option D is correct because it uses VPC peering to directly connect the three US VPCs to the two Asia VPCs, ensuring no access to other VPCs. This approach is cost-effective as it avoids the recurring costs of transit gateways and their attachments.
- Option A is invalid because a transit gateway cannot span multiple regions; VPCs in us-west-2 cannot attach to a transit gateway in ap-northeast-1.
- Option B involves transit gateways in both regions and inter-region peering, which incurs higher costs for gateways, attachments, and data transfer compared to VPC peering.
- Option C creates a full mesh of peering connections, which violates the requirement to avoid unnecessary VPC access and increases costs with redundant connections.
Key Points:
- VPC peering is cost-effective for limited cross-region connections.
- Transit gateways introduce additional costs and complexity unless many VPCs are involved.
- Non-overlapping CIDR ranges simplify routing in peering configurations.
Answer
The correct answer is: D