ANS-C01 Network Implementation Practice Question
A company has a Direct Connect connection with a private VIF to a VPC. The on-premises network uses BGP to advertise its prefixes. Recently, the on-premises router started advertising a more specific route (10.0.0.0/24) that overlaps with the VPC's CIDR (10.0.0.0/16). What is the impact on traffic destined to 10.0.0.5?
⚠ Common exam trap
The ANS-C01 exam often tests the misconception that a more specific BGP route will cause the instance to become unreachable or blackholed, but the actual impact is asymmetric routing where return traffic is forced out through Direct Connect.
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
✓
Return traffic from the instance to on-premises is routed through Direct Connect instead of staying within the VPC.
When an on-premises router advertises a more specific route (10.0.0.0/24) via BGP over a Direct Connect private VIF, the VPC propagates this route into its route tables. For traffic destined to 10.0.0.5, the VPC now has a more specific route (10.0.0.0/24) pointing to the virtual private gateway (VGW), overriding the local VPC route (10.0.0.0/16). This causes return traffic from the instance to on-premises to be routed through Direct Connect instead of staying within the VPC, as the VPC's route table prefers the longest prefix match.
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 instance becomes unreachable from on-premises.
Why it's wrong here
On-premises still has connectivity.
- ✓
Return traffic from the instance to on-premises is routed through Direct Connect instead of staying within the VPC.
Why this is correct
More specific route is preferred.
- ✗
Traffic destined to the instance is blackholed.
Why it's wrong here
Traffic will still flow but via on-premises.
- ✗
Traffic is load-balanced between the VPC and Direct Connect.
Why it's wrong here
No load balancing; route selection is deterministic.
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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.