AWS Certified Advanced Networking Specialty Practice Exam

What must be corrected to ensure that instances in VPC Y can reach instances in VPC Z if they both share IP ranges?

1. Change the subnet size

2. Use different peering connections

3. Create distinct route tables

4. Adjust security group rules

The correct answer is: Create distinct route tables

To enable instances in VPC Y to reach instances in VPC Z when both share overlapping IP ranges, creating distinct route tables is necessary. When IP address ranges overlap, routing can become ambiguous, meaning that data packets may not be able to find a specific destination since the routing paths could incorrectly identify the intended target. By creating distinct route tables, you can explicitly define the routing paths for each VPC. This allows for more granular control over how traffic flows between the two VPCs and ensures that instances can be reached despite the overlapping IP ranges. The route tables will direct traffic based on the intended destination and ensure that instances in one VPC can communicate with instances in another VPC properly. In contrast, changing the subnet size does not directly address the routing ambiguity caused by overlapping IP ranges. Using different peering connections does not solve the problem for VPCs sharing overlapping ranges; simply establishing peering connections without managing the routing will not resolve the issue. Lastly, adjusting security group rules involves configurations that permit or deny traffic based on security policies but does not address the central problem of overlapping address spaces preventing effective routing.