ANS-C01 Network Design Practice Question
A company is designing a multi-account architecture using AWS Transit Gateway. They need to isolate development and production environments but allow shared services account access to both. What is the most scalable and secure design?
⚠ Common exam trap
It's easy for candidates to assume separate route tables on a single Transit Gateway provide full isolation, but AWS explicitly warns that route tables share the same data plane and misconfigurations can leak traffic, so the exam expects two Transit Gateways for hard isolation between environments.
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
✓
Create two Transit Gateways: one for development and one for production. Share the Transit Gateways with the shared services account via AWS Resource Access Manager.
Using two separate Transit Gateways (one for dev, one for prod) provides complete network isolation between environments at the routing layer, while AWS Resource Access Manager (RAM) allows the shared services account to attach its VPC to both Transit Gateways. This design is scalable as each environment can grow independently without route table conflicts, and secure because there is no transitive routing path between dev and prod. A single Transit Gateway with separate route tables (Option A) still shares the same data plane, introducing risk of misconfiguration or route leaks, whereas two Transit Gateways enforce hard isolation.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
Use a single Transit Gateway and configure separate route tables for each environment, attaching VPCs from each account.
Why it's wrong here
Wrong: Single Transit Gateway shares the same infrastructure, reducing isolation.
- ✗
Use a single Transit Gateway with one route table for all environments and implement security groups to isolate traffic.
Why it's wrong here
Wrong: Security groups are not a substitute for network isolation.
- ✓
Create two Transit Gateways: one for development and one for production. Share the Transit Gateways with the shared services account via AWS Resource Access Manager.
Why this is correct
Correct: Separate Transit Gateways provide full isolation, and RAM enables shared services.
- ✗
Use VPC Peering between each VPC and the shared services VPC, and set up Internet Gateway for each environment.
Why it's wrong here
Wrong: VPC Peering does not scale well and requires full mesh.
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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.