ANS-C01 Network Implementation Practice Question
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?
⚠ Common exam trap
Many candidates confuse BGP attributes that influence inbound vs. outbound traffic: candidates often incorrectly apply local preference (outbound) or MED (inbound but with different semantics) instead of AS path prepending, which is the standard method for controlling inbound path selection in a multi-homed BGP setup.
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
✓
Prepend the AS path on the secondary connection's BGP advertisements
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.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✓
Prepend the AS path on the secondary connection's BGP advertisements
Why this is correct
AS path prepending makes the secondary path less preferred; the primary will be used, and failover/failback occurs automatically.
- ✗
Set a higher MED value on the primary connection's BGP advertisements
Why it's wrong here
MED is used to influence inbound traffic from multiple entry points, but AWS typically ignores MED from different ASes.
- ✗
Set a higher local preference on the secondary connection's BGP advertisements
Why it's wrong here
Local preference is used to influence inbound traffic within an AS, not outbound to AWS.
- ✗
Use BGP communities to tag routes and manipulate preference on AWS side
Why it's wrong here
BGP communities can influence routing policies but are not typically used for simple active/passive failover with automatic failback.
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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.