A company has two VPCs: VPC A with CIDR block and VPC B with CIDR block . The VPCs are connected using an AWS Transit Gateway. A SysOps administrator is troubleshooting a connectivity issue where Amazon EC2 instances in a private subnet () of VPC A cannot connect to an Amazon RDS DB instance in a private subnet () of VPC B.
The administrator verifies the following configuration details:
- The Transit Gateway route tables show active attachments and successful route propagation for both VPCs.
- The subnet route table for VPC A has a route for pointing to the Transit Gateway.
- The subnet route table for VPC B has a route for pointing to the Transit Gateway.
- The Network ACLs (NACLs) for all subnets in both VPCs allow all inbound and outbound traffic.
Which of the following is the most likely cause of this connection failure?
- The security group associated with the RDS DB instance in VPC B references the security group ID of the EC2 instances in VPC A as its source.Cevap
- BThe security group associated with the RDS DB instance in VPC B is missing an outbound rule to allow return traffic to the ephemeral ports of the EC2 instances.
- CThe route table associated with the RDS DB instance's subnet in VPC B is missing a route targeting the Internet Gateway (IGW) for return traffic.
- DThe route table associated with the RDS DB instance's subnet in VPC B has a default route () pointing to a NAT Gateway, which overrides the Transit Gateway route.