ANS-C01 Network Implementation Practice Question
A company is implementing a hybrid network architecture with AWS Direct Connect and a VPN backup. The company has two Direct Connect connections from different providers terminating at two AWS Direct Connect locations, each connecting to a separate AWS Transit Gateway in the same region. The VPCs are attached to both transit gateways. The company needs to ensure that traffic from on-premises to VPCs uses the primary Direct Connect connection when available and fails over to the secondary Direct Connect connection, then to the VPN. How should the company configure routing to achieve this?
⚠ Common exam trap
Many candidates think static routes with metrics can be used in transit gateway route tables to influence path selection, but BGP-based routing in hybrid networks requires manipulating BGP attributes like AS_PATH, not static route metrics.
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
✓
Configure BGP AS_PATH prepending on the secondary Direct Connect and VPN connections to make them less preferred than the primary Direct Connect.
BGP AS_PATH prepending on the secondary Direct Connect and VPN connections artificially increases the AS path length, making those routes less preferred in the BGP best-path selection process. This ensures that the primary Direct Connect connection is chosen for traffic from on-premises to VPCs when available, with automatic failover to the secondary Direct Connect and then to the VPN as the least preferred path.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✓
Configure BGP AS_PATH prepending on the secondary Direct Connect and VPN connections to make them less preferred than the primary Direct Connect.
Why this is correct
AS_PATH prepending influences BGP best path selection.
- ✗
Disable route propagation from the VPN to the transit gateway route tables, and rely on the Direct Connect connections only.
Why it's wrong here
Does not provide failover priority among Direct Connect connections.
- ✗
Configure equal-cost multipath (ECMP) routing across all three connections to load balance traffic.
Why it's wrong here
ECMP does not provide failover priority; all paths active simultaneously.
- ✗
Use static routes in the transit gateway route tables with higher metric values for the secondary Direct Connect and VPN.
Why it's wrong here
Static routes are not supported with Direct Connect; BGP is mandatory.
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Same concept, more angles
2 more ways 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. A company is designing a hybrid network architecture that requires high availability and low latency between its on-premises data center and AWS. They have two redundant 1 Gbps AWS Direct Connect connections. The company wants to use BGP to advertise the same prefix from both locations to AWS. How should they configure the BGP attributes to ensure active/passive failover with automatic failback?
medium- ✓ A.Prepend the AS path on the secondary connection's BGP advertisements
- B.Set a higher MED value on the primary connection's BGP advertisements
- C.Set a higher local preference on the secondary connection's BGP advertisements
- D.Use BGP communities to tag routes and manipulate preference on AWS side
Why A: AS path prepending on the secondary connection makes the BGP path longer, causing AWS to prefer the primary connection for inbound traffic. This achieves active/passive failover: if the primary fails, the shorter AS path on the secondary becomes preferred, and automatic failback occurs when the primary recovers and its shorter AS path is re-advertised.
Variation 2. A network engineer is designing a hybrid network architecture that connects an on-premises data center to AWS using AWS Direct Connect and a VPN connection as a backup. The on-premises network uses BGP to advertise routes to AWS. Which of the following are best practices for this setup? (Choose TWO.)
medium- A.Advertise the same routes over both connections with identical BGP attributes.
- ✓ B.Use different BGP ASNs for the Direct Connect and VPN connections.
- C.Use the VPN connection as the primary path and Direct Connect as the backup.
- D.Use the same BGP ASN for both the Direct Connect and VPN connections.
- ✓ E.Configure BGP attributes to ensure that the Direct Connect path is preferred over the VPN path.
Why B: Using different BGP ASNs for the Direct Connect and VPN connections prevents BGP from treating the two connections as a single eBGP session, which would cause routing loops or suboptimal path selection. This separation allows AWS to distinguish between the two paths and apply independent routing policies. Option E is correct because configuring BGP attributes (such as AS path prepending or MED) on the Direct Connect path ensures it is preferred over the VPN backup, aligning with the design goal of using Direct Connect as the primary link.
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.