VPC Peering Connection

Answer - D.

Since transitive peering is not allowed, you can use a proxy instance to forward the requests.

Options A,B and C are all invalid , because as per the AWS Documentation, this is the rule of transitive peering.

For more information on VPC peering configurations, please visit the below URL.

The VPC peering connections between VPC A and VPC B and between VPC A and VPC C create a network topology where VPC B and VPC C are not directly connected to each other. The VPC peering connections are non-transitive, meaning that VPC B cannot communicate with VPC C directly.

Option A is false since VPC B and VPC C are not directly connected, instances launched in VPC B cannot reach instances in VPC C.

Option B is partially true. Instances launched in VPC B can reach instances in VPC C if the right routing entries are present in the route tables of both VPCs. Each VPC must have a route to the other VPC CIDR block via the respective VPC peering connection.

Option C is false. Security groups control inbound and outbound traffic at the instance level, not at the VPC peering connection level. Even if the Security Groups rules are present for the instances, VPC B and VPC C are not directly connected, so the instances launched in VPC B cannot reach instances in VPC C.

Option D is also partially true. Instances launched in VPC B can reach instances in VPC C via a proxy instance in VPC A. The proxy instance can act as a router or a NAT device between VPC B and VPC C. The proxy instance must be configured with the appropriate routing and security group rules to allow traffic to flow between VPC B and VPC C.

Therefore, the correct answer is B and D.