AWS Certified SysOps Administrator – AssociateNetworking and Content DeliveryHard
A company is hosting a multi-tier application in a VPC. The web tier is in public subnets, and the application and database tiers are in private subnets. The application tier needs to connect to the database tier, and both tiers need to be able to communicate with backend services hosted in another VPC in the same AWS Region. The solution must be highly available and support transitive routing. Which AWS service should be used to connect the two VPCs?
- AVPN Gateway
- BVPC Peering
- CAWS Transit Gateway
- DAWS Direct Connect
Show answer & explanationAnswer & explanation
Correct answer: C. AWS Transit Gateway
AWS Transit Gateway is designed for connecting multiple VPCs and on-premises networks in a hub-and-spoke model, supporting transitive routing. This means that resources in one VPC connected to the Transit Gateway can communicate with resources in another VPC connected to the same Transit Gateway, which is not possible with VPC Peering. Given the need for communication between multiple tiers across VPCs and transitive routing, Transit Gateway is the appropriate solution.
Why the other options are wrong
- A. VPN Gateway is typically used for Site-to-Site VPN connections to on-premises networks or for connecting individual VPCs; it doesn't provide the centralized, transitive routing capabilities of Transit Gateway for multiple VPCs.
- B. VPC Peering creates a direct network link between two VPCs. However, it does not support transitive routing, meaning VPC A cannot communicate with VPC C via VPC B if A and B are peered, and B and C are peered.
- D. Direct Connect is for connecting on-premises networks to AWS, not for connecting two VPCs within AWS.
AWS Transit Gateway
A network transit hub that you can use to interconnect your virtual private clouds (VPCs) and on-premises networks to a single gateway.
- Supports transitive routing between connected VPCs.
- Simplifies network architecture for many VPCs.
- Acts as a central hub for network connectivity.
Memory trick: Transit Gateway is the central hub for all your VPC routes.