ANS-C01 Network Implementation Practice Question
A company has a centralized inspection VPC architecture where all traffic from spoke VPCs is routed through a Transit Gateway to a centralized VPC that hosts firewall appliances (NGFW). The company needs to inspect traffic between two instances in the same spoke VPC. What is the simplest way to achieve this?
⚠ Common exam trap
AWS often tests the misconception that VPC peering can be used for transitive routing or that a Gateway Load Balancer alone can redirect traffic within the same VPC, but the key trap here is that candidates overlook the Transit Gateway's ability to hairpin traffic from the same spoke VPC through a central inspection VPC using proper route table configurations.
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
✓
Use AWS Transit Gateway with VPC attachments and configure route tables to force traffic between the two instances through the inspection VPC.
AWS Transit Gateway can route traffic between instances in the same spoke VPC by using VPC attachments and route tables to force the traffic through the centralized inspection VPC. This is achieved by configuring the spoke VPC's route table to send inter-instance traffic to the Transit Gateway, which then forwards it to the inspection VPC for firewall inspection before returning it to the destination instance. This approach avoids the need for additional appliances or complex routing within the spoke VPC itself.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
Deploy a Gateway Load Balancer (GWLB) in the spoke VPC and route traffic to it.
Why it's wrong here
GWLB is used for transparent inspection, but it requires additional configuration and does not inherently route traffic to the inspection VPC.
- ✓
Use AWS Transit Gateway with VPC attachments and configure route tables to force traffic between the two instances through the inspection VPC.
Why this is correct
Transit Gateway can be configured with route tables that send inter-VPC traffic to the inspection VPC for firewall inspection.
- ✗
Enable VPC peering and use route propagation to send traffic to the inspection VPC.
Why it's wrong here
VPC peering does not support transitive routing; route propagation is for VPN.
- ✗
Create a VPC peering connection between the two instances' VPCs.
Why it's wrong here
VPC peering bypasses the Transit Gateway and the inspection VPC, so traffic will not be inspected.
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JA
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.