ANS-C01 Network Design Practice Question
A company is using AWS Transit Gateway to connect multiple VPCs. They notice that traffic between two VPCs in different Availability Zones is taking a suboptimal path, resulting in cross-AZ data transfer costs. How can they optimize the path and reduce costs?
⚠ Common exam trap
Test-takers frequently confuse Transit Gateway's regional nature with AZ-specific routing, assuming that Transit Gateway can be pinned to a single AZ, when in fact it always routes traffic through the AZ of the attachment's ENI, and cross-AZ costs are incurred unless resources are in the same AZ.
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 Availability Zone affinity by launching resources in the same AZ and using Transit Gateway to route within the same AZ.
Configuring resources in the same Availability Zone (AZ) and using Transit Gateway to route within that AZ eliminates cross-AZ data transfer costs. AWS Transit Gateway charges for cross-AZ traffic, so keeping traffic local to a single AZ avoids these charges while still leveraging Transit Gateway for centralized routing.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
Replace Transit Gateway with VPC Peering between the VPCs.
Why it's wrong here
Wrong: VPC Peering does not solve the cross-AZ issue.
- ✓
Use Availability Zone affinity by launching resources in the same AZ and using Transit Gateway to route within the same AZ.
Why this is correct
Correct: Keeps traffic within AZ, avoiding cross-AZ charges.
- ✗
Enable Transit Gateway multicast to replicate traffic across AZs.
Why it's wrong here
Wrong: Multicast is for one-to-many, not for cost optimization.
- ✗
Configure the Transit Gateway to use a single Availability Zone for all attachments.
Why it's wrong here
Wrong: Transit Gateway is not AZ-scoped.
Go deeper
Related to this question
About these practice questions
One of 1,621 original ANS-C01 practice questions on Courseiva, each with a full explanation and wrong-answer analysis — not exam dumps or protected exam content. Learn why practice questions differ from exam dumps →
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.