ANS-C01 Network Management and Operations Practice Question
A company is using AWS Transit Gateway to connect multiple VPCs and on-premises networks. After a network change, some VPCs cannot reach the on-premises network. The Transit Gateway route table shows the correct association and propagation. What is the most likely cause?
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
✓
The VPC route tables do not have a route pointing to the Transit Gateway
The VPC route tables do not have a route pointing to the Transit Gateway. Even though the Transit Gateway route table has correct associations and propagations, traffic from VPCs to on-premises requires a route in the VPC route tables pointing to the Transit Gateway attachment. Without such a route, VPCs cannot send traffic to the Transit Gateway, causing connectivity loss. Option A is incorrect because the attachment state is fine if the route table shows correct association. Option B is incorrect because insufficient bandwidth would cause performance issues, not complete loss of connectivity. Option C is incorrect because a down BGP session would affect route propagation, but the Transit Gateway route table already shows correct propagation, implying BGP is functioning.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
The Transit Gateway attachment is in a failed state
Why it's wrong here
Attachment state would be visible and affect all VPCs, not just some.
- ✗
The VPN connection to the on-premises network has insufficient bandwidth
Why it's wrong here
Bandwidth does not cause complete connectivity failure.
- ✗
The BGP session between the Transit Gateway and on-premises router is down
Why it's wrong here
If BGP were down, all VPCs would be affected, not just some.
- ✓
The VPC route tables do not have a route pointing to the Transit Gateway
Why this is correct
Without a route to the Transit Gateway, traffic from the VPC cannot reach on-premises networks.
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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.