ANS-C01 Network Implementation Practice Question
A company has a Direct Connect connection with a private virtual interface (VIF) to a VPC. The VPC uses a virtual private gateway (VGW). The on-premises network advertises a route to a specific subnet (10.0.0.0/24) via BGP. However, traffic from the VPC to that subnet is failing. What should the network engineer check first?
⚠ Common exam trap
Many candidates assume a working BGP session and VIF automatically make the route available in the VPC, overlooking the requirement for route propagation to be explicitly enabled on the VPC's subnet route tables.
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
✓
Verify that route propagation is enabled on the VPC's route tables associated with the subnets.
The most common cause of traffic failure from a VPC to an on-premises subnet over Direct Connect is that the VPC route tables do not have a route for the on-premises subnet. Even if the VGW is attached and BGP is established, the VPC subnets must have route propagation enabled on their route tables to automatically learn the routes advertised by the on-premises network via BGP. Without this, the VPC has no path to send traffic to the 10.0.0.0/24 subnet.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
Verify that the customer gateway device is advertising the subnet route.
Why it's wrong here
The on-premises router advertises; but the issue is on the AWS side propagation.
- ✗
Verify that the virtual interface is in the 'available' state and BGP session is established.
Why it's wrong here
BGP session might be up but routes not propagated to VPC route tables.
- ✗
Verify that the VGW is attached to the VPC.
Why it's wrong here
Attachment is required but doesn't ensure routes are propagated into the route tables.
- ✓
Verify that route propagation is enabled on the VPC's route tables associated with the subnets.
Why this is correct
Without route propagation, the BGP routes from Direct Connect are not added to the route tables.
Visual reference
Go deeper
Related to this question
About these practice questions
Courseiva writes every ANS-C01 question from scratch — 1,621 in total, each with an explanation and a wrong-answer breakdown. None are copied from real exams or dumps. Learn why practice questions differ from exam dumps →
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.