ANS-C01 Network Design Practice Question
A company has a VPC with a CIDR of 10.0.0.0/16. They need to peer with another VPC that has a CIDR of 10.0.0.0/24. What will happen?
⚠ Common exam trap
The ANS-C01 exam often tests the misconception that overlapping CIDRs are allowed in VPC peering but simply cause routing issues later, when in fact the peering creation itself is blocked by the AWS API.
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
✓
The peering connection will fail because the CIDRs overlap.
AWS VPC peering requires that the CIDR blocks of the two VPCs do not overlap. When both VPCs use the same IP range (10.0.0.0/16 and 10.0.0.0/24), the peering connection request will fail because overlapping CIDRs create routing ambiguity and are not supported by the VPC peering service. This is a hard limit enforced at the time of peering creation, not during route table configuration.
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 peering connection will be established, but only the first VPC's CIDR will be used.
Why it's wrong here
Peering requires non-overlapping CIDRs.
- ✗
The peering connection will be established, but routes with overlapping CIDRs will not be added automatically.
Why it's wrong here
AWS does not allow peering with overlapping CIDRs.
- ✓
The peering connection will fail because the CIDRs overlap.
Why this is correct
VPC Peering requires non-overlapping IP address ranges.
- ✗
The peering connection will be established, and the overlapping CIDRs will be ignored.
Why it's wrong here
Overlapping CIDRs prevent peering.
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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.