This ANS-C01 practice question tests your understanding of network design. The scenario asks you to isolate a root cause — eliminate options that address a different problem before choosing. After answering, compare your reasoning against the explanation and wrong-answer breakdown below. Once you have made your selection, read the full explanation to reinforce the concept and understand why each distractor is designed to mislead on exam day.
A company is designing a multi-region architecture with VPCs in us-east-1 and eu-west-1. The company needs low-latency connectivity between the VPCs and wants to avoid traffic over the public internet. The VPCs have overlapping CIDR blocks (10.0.0.0/16). Which solution should the network engineer recommend?
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Set up an AWS Transit Gateway in each region and connect them via a VPN attachment.
Option A is correct because AWS Transit Gateway supports inter-region peering attachments that use the AWS global network backbone, providing low-latency, private connectivity between VPCs in different regions. Even when VPCs have overlapping CIDR blocks, Transit Gateway can handle this through route table isolation and network segmentation (e.g., using separate route tables for each VPC attachment), which VPC peering cannot do. VPN attachments between Transit Gateways in each region establish encrypted tunnels over the AWS backbone, avoiding the public internet.
Key principle: Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
✓
Set up an AWS Transit Gateway in each region and connect them via a VPN attachment.
Why this is correct
Transit Gateway with VPN can handle overlapping CIDRs.
Related concept
Read the scenario before looking for a memorised answer.
✗
Use a Direct Connect connection between the regions.
Why it's wrong here
Direct Connect does not solve overlapping CIDRs.
✗
Use VPC peering between the two VPCs.
Why it's wrong here
Overlapping CIDRs prevent VPC peering.
✗
Place all resources in a single VPC with multiple Availability Zones.
Why it's wrong here
Not applicable for multi-region.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates assume VPC peering is always the simplest solution, but they overlook the critical requirement that VPC peering cannot work with overlapping CIDR blocks, making Transit Gateway with VPN attachments the only viable option for this scenario.
Detailed technical explanation
How to think about this question
Transit Gateway inter-region peering uses the AWS global network to route traffic, with each peering attachment supporting up to 20 Gbps of bandwidth and less than 10 ms latency between US and EU regions. The VPN attachment between Transit Gateways can use IPsec with AES-256 encryption, and when combined with BGP dynamic routing, it allows for failover and load balancing across multiple tunnels. Overlapping CIDRs are handled by associating each VPC attachment with a separate route table, ensuring traffic is isolated per VPC even if IP ranges conflict.
KKey Concepts to Remember
Read the scenario before looking for a memorised answer.
Find the constraint that changes the correct option.
Eliminate answers that are true in general but not in this case.
TExam Day Tips
→Watch for words such as best, first, most likely and least administrative effort.
→Review why wrong options are wrong, not only why the correct option is correct.
Key takeaway
Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Real-world example
How this comes up in practice
An e-commerce site experiences heavy traffic on Black Friday and near-zero traffic during off-peak weeks. Rather than provisioning permanent large VMs, the team uses auto-scaling groups that add capacity automatically under load and reduce it overnight. Questions like this test whether you understand elasticity, availability zones, and cloud compute scaling patterns.
What to study next
Got this wrong? Here's your next step.
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
Network Design — This question tests Network Design — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: Set up an AWS Transit Gateway in each region and connect them via a VPN attachment. — Option A is correct because AWS Transit Gateway supports inter-region peering attachments that use the AWS global network backbone, providing low-latency, private connectivity between VPCs in different regions. Even when VPCs have overlapping CIDR blocks, Transit Gateway can handle this through route table isolation and network segmentation (e.g., using separate route tables for each VPC attachment), which VPC peering cannot do. VPN attachments between Transit Gateways in each region establish encrypted tunnels over the AWS backbone, avoiding the public internet.
What should I do if I get this ANS-C01 question wrong?
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
What is the key concept behind this question?
Read the scenario before looking for a memorised answer.
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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.
Question Discussion
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