ANS-C01 Network Implementation Practice Question
A company has a VPC with an IPv6 CIDR block and wants to provide internet access to instances in a private subnet using an egress-only internet gateway. Which of the following must be configured correctly?
⚠ Common exam trap
The ANS-C01 exam often tests the misconception that an egress-only internet gateway requires an IPv6 address assignment or that it behaves like a NAT gateway for IPv6, leading candidates to choose Option D or Option A, when in fact it is a stateless gateway that only requires a route table entry.
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
✓
Add a default route (::/0) in the private subnet's route table pointing to the egress-only internet gateway.
An egress-only internet gateway (EIG) is a horizontally scaled, redundant VPC component that allows outbound-only IPv6 traffic from instances in a private subnet to the internet, while preventing unsolicited inbound connections. To use it, you must add a default route (::/0) in the private subnet's route table pointing to the EIG, which directs all outbound IPv6 traffic through the gateway. This configuration ensures that instances can initiate outbound IPv6 connections (e.g., to download updates) but cannot be reached from the internet.
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 NAT64 on the VPC to translate IPv6 to IPv4.
Why it's wrong here
NAT64 is for IPv6 to IPv4 translation, not needed for native IPv6 access.
- ✗
Enable route propagation for the egress-only internet gateway in the route table.
Why it's wrong here
Route propagation does not apply to egress-only internet gateways; routes are static.
- ✓
Add a default route (::/0) in the private subnet's route table pointing to the egress-only internet gateway.
Why this is correct
This allows IPv6 traffic from the private subnet to reach the internet outbound.
- ✗
Assign an IPv6 address to the egress-only internet gateway.
Why it's wrong here
Egress-only internet gateways do not have IPv6 addresses; they are virtual devices.
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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.