ANS-C01 Network Implementation Practice Question
A company uses AWS Transit Gateway with multiple VPC attachments and a VPN attachment to an on-premises network. The on-premises network advertises the same prefix via two separate VPN connections for redundancy. The TGW route table shows both routes as active. Traffic from a VPC to on-premises is not load-balanced and prefers one connection. Which THREE actions would help achieve active-active load balancing? (Choose 3.)
⚠ Common exam trap
It's easy for candidates to assume BGP weight (a Cisco-proprietary attribute) can be used on AWS Transit Gateway, but AWS only supports standard BGP attributes and does not implement weight, making option C a distractor.
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 preferred VPN connection to make it less preferred
BGP AS_PATH prepending artificially increases the AS path length for routes advertised over the preferred VPN connection, making them less preferred by BGP's path selection algorithm. This causes the Transit Gateway to prefer the other VPN connection for those prefixes, enabling active-active load balancing when combined with ECMP.
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 preferred VPN connection to make it less preferred
Why this is correct
AS_PATH prepending can make one path appear longer.
- ✓
Enable equal-cost multi-path (ECMP) routing on the Transit Gateway route table
Why this is correct
ECMP enables load balancing across equal-cost routes.
- ✗
Set a higher BGP weight on the less preferred connection
Why it's wrong here
Weight is Cisco proprietary and not supported on AWS VPN.
- ✗
Use static routes for both VPN connections instead of BGP
Why it's wrong here
Static routes do not support ECMP or dynamic load balancing.
- ✓
Adjust the BGP Multi-Exit Discriminator (MED) attribute on the on-premises routers
Why this is correct
MED influences inbound traffic path selection.
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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.