AWS Certified SysOps Administrator – Associate (legacy) — Question 401

A SysOps Administrator needs Amazon EC2 instances in two different VPCs in private subnets to be able to communicate. A peering connection between the two
VPCs has been created using the AWS Management Console and shows a status of Active. The instances are still unable to send traffic to each other.
Why are the EC2 instances unable to communicate?

Answer options

• A. One or both of the VPCs do not have an Internet Gateway attached
• B. The route tables have not been updated
• C. The peering connection has not been properly tagged
• D. One or both of the instances do not have an Elastic IP address assigned

Correct answer: B

Explanation

After a VPC peering connection is established and active, route tables in both VPCs must be manually updated to point to the peer VPC CIDR block via the peering connection. Without these route table entries, the EC2 instances will not know how to route traffic to the destination VPC. Internet Gateways, Elastic IPs, and tags are not required for internal private communication over a VPC peering connection.