ANS-C01 Network Implementation Practice Question
A company has a VPC with a CIDR of 10.0.0.0/16. They need to connect to a partner's VPC with CIDR 10.0.0.0/16 using a VPC peering connection. What is the issue with this configuration?
⚠ Common exam trap
The ANS-C01 exam often tests the overlapping CIDR restriction for VPC peering, and the trap here is that candidates may focus on transitive routing or regional limitations instead of recognizing that the fundamental prerequisite of non-overlapping IP ranges is violated.
Answer choices
Why each option matters
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Overlapping CIDR ranges are not supported for VPC peering
VPC peering requires that the CIDR blocks of the peered VPCs do not overlap. In this case, both VPCs use 10.0.0.0/16, which creates an identical address space. When routes are added to the route tables for the peering connection, the destination CIDR would be ambiguous, and the VPC cannot distinguish between local resources and those in the peered VPC, leading to routing conflicts. AWS explicitly rejects peering requests between VPCs with overlapping or identical CIDR ranges.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
The company has reached the maximum number of VPC peering connections
Why it's wrong here
The limit is high and not mentioned.
- ✗
VPC peering is only supported within the same region
Why it's wrong here
VPC peering supports cross-region connections.
- ✗
VPC peering does not support transitive routing
Why it's wrong here
While transitive routing is not supported, the primary issue is overlapping CIDRs.
- ✓
Overlapping CIDR ranges are not supported for VPC peering
Why this is correct
VPC peering requires non-overlapping CIDR blocks to enable routing between them.
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Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
This ANS-C01 practice question is part of Courseiva's free Amazon Web Services certification practice question bank. Courseiva provides original exam-style practice questions with explanations, topic-based practice, mock exams, readiness tracking, and study analytics to help learners prepare for the ANS-C01 exam.