ANS-C01 Network Implementation Practice Question
A company has a Direct Connect connection with a private VIF to a VPC. The company also has a Site-to-Site VPN connection to the same VPC as a backup. During a failover test, traffic from on-premises to the VPC continues to use the Direct Connect even after it is intentionally failed. The BGP timers are set to default values. What is the most likely cause?
⚠ Common exam trap
The ANS-C01 exam often tests the misconception that a physical link failure is required for BGP to withdraw routes, but the trap here is that BGP can remain established even when the data plane is broken, so the backup VPN never activates.
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 BGP session with the Direct Connect router is still established because the physical link is up, but the link is not forwarding traffic.
The Direct Connect physical link is still up, so the BGP session remains established even though the link is not forwarding traffic. With default BGP timers (keepalive 60s, hold 180s), the session does not time out, so the VPC continues to receive the Direct Connect route and prefers it over the VPN backup. A failover requires either the BGP session to go down or the route to be withdrawn, neither of which occurs when only the data plane fails.
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 Direct Connect route is more specific than the VPN route.
Why it's wrong here
More specific routes are preferred, but if both are the same prefix, the BGP decision process would consider other attributes.
- ✗
The VPN BGP route has a longer AS path than the Direct Connect route.
Why it's wrong here
Longer AS path makes the route less preferred, so traffic would still go via Direct Connect.
- ✗
The VPN route has a lower local preference than the Direct Connect route.
Why it's wrong here
Lower local preference makes the route less preferred, so traffic would still go via Direct Connect.
- ✓
The BGP session with the Direct Connect router is still established because the physical link is up, but the link is not forwarding traffic.
Why this is correct
If the BGP session remains established, routes are still advertised and the Direct Connect route remains in the routing table, causing traffic to still be sent.
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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.