Steps to Set Up Cross-Account Transit Gateway with RAM
A company is designing a multi-account AWS environment using AWS Transit Gateway. They want to centralize network management and ensure that VPCs in different accounts can communicate. Which THREE steps are required to achieve this? (Select THREE.)
Quick Answer
The answer is to share the Transit Gateway using Resource Access Manager, create a Transit Gateway route table, and associate the VPC attachments with that route table. This multi-account Transit Gateway setup centralizes network management by allowing a single Transit Gateway in a hub account to be shared with multiple spoke accounts via RAM, eliminating the need for VPC peering. Each VPC attachment must then be associated with a route table to propagate and route traffic correctly across accounts. On the AWS Certified Advanced Networking Specialty ANS-C01 exam, this scenario tests your understanding of the shared services model and the distinction between Transit Gateway and VPC peering—a common trap is assuming you need a separate Transit Gateway per account or that VPC peering is still required. Remember the mnemonic: Share, Table, Attach—you share the gateway, build a route table, and attach the VPCs to it.
⚠ Common exam trap
The trap here is that candidates might think each account needs its own Transit Gateway (Option C) or that VPC peering is required to connect to the Transit Gateway (Option E), when in fact a single shared Transit Gateway with VPC attachments is the correct approach.
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 a Transit Gateway in the central networking account
The Transit Gateway must be created in a central networking account to serve as the hub for all VPC traffic. This centralizes routing and simplifies network management across the multi-account environment.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✓
Create a Transit Gateway in the central networking account
Why this is correct
A central Transit Gateway is created in the networking account.
- ✓
Use AWS Resource Access Manager (RAM) to share the Transit Gateway with other accounts
Why this is correct
RAM allows sharing the Transit Gateway with other accounts.
- ✗
Create a separate Transit Gateway in each account and peer them together
Why it's wrong here
Creating a separate Transit Gateway in each account and peering them introduces inter-Region or inter-account routing complexity and breaks centralised management, because each Transit Gateway operates independently with its own route tables and attachment policies, whereas the correct approach uses a single shared Transit Gateway in a central account with Resource Access Manager to simplify cross-account VPC connectivity. This option is tempting because Transit Gateway peering is a valid method for connecting Transit Gateways across different AWS Regions or separate administrative domains, and would be correct if the requirement were to connect isolated Transit Gateways in distinct Regions rather than to centralise management within a single Region.
- ✓
Create a Transit Gateway route table and associate VPC attachments
Why this is correct
Route tables control traffic between attachments.
- ✗
Create a VPC peering connection between each VPC and the Transit Gateway
Why it's wrong here
VPCs attach to the Transit Gateway, not via VPC peering.
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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. Which THREE of the following are considerations when designing a multi-account VPC architecture using AWS Transit Gateway? (Choose 3.)
hard- ✓ A.Transit Gateway can be integrated with Direct Connect Gateway
- B.Each VPC must have a unique route table
- ✓ C.Transit Gateway supports cross-account VPC attachments
- ✓ D.Route tables can be used to isolate VPCs from each other
- E.VPCs with overlapping CIDR blocks can be attached
Why A: AWS Transit Gateway acts as a central hub for interconnecting VPCs and on-premises networks. It can be integrated with Direct Connect Gateway, allowing a single Direct Connect connection to reach multiple VPCs attached to the Transit Gateway, simplifying hybrid network design and reducing operational overhead.
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.