ANS-C01 Network Implementation Practice Question
A company has a VPC with both IPv4 and IPv6 CIDRs. They need to allow outbound IPv6 traffic from private subnets to the internet. What should they use?
⚠ Common exam trap
It's easy for candidates to confuse the egress-only internet gateway with a NAT gateway, assuming NAT can handle IPv6, or they incorrectly select an internet gateway thinking it can be restricted to outbound-only traffic, but AWS does not support such a configuration for IPv6.
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
✓
An egress-only internet gateway.
An egress-only internet gateway (EIGW) is a horizontally scaled, redundant VPC component that allows outbound IPv6 traffic from instances in a VPC to the internet, while preventing the internet from initiating an IPv6 connection to those instances. It is specifically designed for IPv6 traffic and must be used with a route table entry that directs all outbound IPv6 traffic (::/0) to the EIGW. Unlike an internet gateway, an EIGW does not support inbound IPv6 connections, making it the correct choice for private subnets that need outbound-only IPv6 internet access.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
An internet gateway attached to the VPC.
Why it's wrong here
Internet gateway allows bidirectional traffic, which may pose security risk.
- ✗
A customer-managed prefix list.
Why it's wrong here
Prefix list is for IP address grouping, not for internet access.
- ✗
A NAT gateway in a public subnet.
Why it's wrong here
NAT gateway does not support IPv6.
- ✓
An egress-only internet gateway.
Why this is correct
Designed for outbound-only IPv6 traffic from private subnets.
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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.