ANS-C01 Network Design Practice Question
A company is deploying a multi-tier web application across multiple AWS accounts. They want to centralize network security by using a shared services VPC with a Transit Gateway. All application VPCs will be attached to the Transit Gateway. The security team needs to inspect and filter traffic between application VPCs. Which solution should be used to meet this requirement?
⚠ Common exam trap
The ANS-C01 exam often tests the misconception that security groups or network ACLs can filter traffic between VPCs, but they are scoped to a single VPC and cannot inspect traffic traversing a Transit Gateway or VPC Peering connection.
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
✓
Deploy a Transit Gateway and attach a central inspection VPC with a firewall appliance. Configure route tables to send inter-VPC traffic through the inspection VPC.
A Transit Gateway with a central inspection VPC allows you to route all inter-VPC traffic through a firewall appliance for inspection. By configuring route tables on the Transit Gateway, you can force traffic between application VPCs to traverse the inspection VPC, enabling centralized security filtering without requiring point-to-point peering or per-VPC rules.
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 Transit Gateway and attach a central inspection VPC with a firewall appliance. Configure route tables to send inter-VPC traffic through the inspection VPC.
Why this is correct
This architecture allows centralized inspection of all traffic between VPCs by routing it through the inspection VPC.
- ✗
Create VPC Peering connections between each pair of application VPCs and apply security groups to the peer connections.
Why it's wrong here
VPC Peering does not support security groups on peer connections; traffic between peered VPCs is filtered by security groups of instances, not centrally.
- ✗
Use security groups in each application VPC to control traffic between VPCs.
Why it's wrong here
Security groups are applied to individual instances and do not filter traffic at the VPC level.
- ✗
Use network ACLs in each application VPC to filter traffic between VPCs.
Why it's wrong here
Network ACLs operate at the subnet level within a VPC and cannot filter traffic between VPCs.
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Same concept, more angles
1 more way this is tested on ANS-C01
These questions test the same concept from different angles. Work through them to make sure you can recognise it however the exam phrases it.
Variation 1. A company is using AWS Organizations to manage multiple accounts. The network team needs to allow a centralized inspection VPC to inspect all traffic between VPCs in different accounts. Which AWS service should be used to route traffic through the inspection VPC?
medium- ✓ A.AWS Transit Gateway
- B.VPC peering connections
- C.AWS PrivateLink
- D.AWS Site-to-Site VPN
Why A: AWS Transit Gateway acts as a central hub for inter-VPC and inter-account traffic, enabling you to attach VPCs from multiple AWS accounts (via AWS Organizations) and route traffic through a centralized inspection VPC. By using Transit Gateway route tables and a dedicated inspection VPC with appliances (e.g., firewall), you can enforce traffic inspection for all cross-account VPC communications without requiring individual peering connections.
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.