This ANS-C01 practice question tests your understanding of network design. Match the stated requirement to the specific cloud service, access model, or configuration option — many options are valid in isolation but not for this scenario. After answering, compare your reasoning against the explanation and wrong-answer breakdown below. Once you have made your selection, read the full explanation to reinforce the concept and understand why each distractor is designed to mislead on exam day.
A solutions architect needs to design a VPC with both IPv4 and IPv6 support. The VPC will have public and private subnets. Resources in private subnets need outbound IPv6 access to the internet. Which combination of resources should be used?
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Internet gateway for public subnets and egress-only internet gateway for private subnets
Option D is correct because an egress-only internet gateway (EIGW) is the AWS-managed service designed specifically to provide outbound-only IPv6 access from private subnets to the internet, while an internet gateway (IGW) handles both inbound and outbound IPv4/IPv6 traffic for public subnets. Unlike a NAT gateway, which only supports IPv4, the EIGW works with IPv6 and prevents any inbound IPv6 connections from the internet, meeting the requirement for outbound-only IPv6 access.
Key principle: Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
✗
Internet gateway for public subnets and VPC gateway endpoints for private subnets
Why it's wrong here
Gateway endpoints are for S3 and DynamoDB, not general internet access.
✗
Internet gateway for public subnets and NAT gateway for private subnets
Internet gateway for both public and private subnets using route tables
Why it's wrong here
Private subnets would be accessible from internet.
✓
Internet gateway for public subnets and egress-only internet gateway for private subnets
Why this is correct
Egress-only internet gateway provides IPv6 outbound access for private subnets.
Related concept
Read the scenario before looking for a memorised answer.
Common exam traps
Common exam trap: answer the scenario, not the keyword
AWS often tests the misconception that a NATgateway can handle IPv6 traffic, but NAT gateways are IPv4-only; the trap here is confusing the IPv4 outbound solution (NAT gateway) with the IPv6 outbound solution (egress-only internet gateway), or assuming an internet gateway can be used in private subnets with route restrictions.
Detailed technical explanation
How to think about this question
An egress-only internet gateway is a horizontally scaled, redundant, and highly available AWS service that uses a stateful firewall to allow outbound IPv6 traffic from instances in a private subnet while dropping any unsolicited inbound IPv6 traffic. It operates at the VPC level and is attached to the VPC, requiring a default route (::/0) in the private subnet's route table pointing to the EIGW. In real-world scenarios, this is critical for workloads like containerized applications or IoT devices that need to reach IPv6-enabled endpoints (e.g., software updates) without exposing internal resources to the public internet.
KKey Concepts to Remember
Read the scenario before looking for a memorised answer.
Find the constraint that changes the correct option.
Eliminate answers that are true in general but not in this case.
TExam Day Tips
→Watch for words such as best, first, most likely and least administrative effort.
→Review why wrong options are wrong, not only why the correct option is correct.
Key takeaway
Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Real-world example
How this comes up in practice
A company's IT admin needs to give a contractor read-only access to production logs without sharing account credentials. Using role-based access control (RBAC) and temporary scoped permissions — not a permanent shared password — is the correct pattern. Questions like this test whether you can apply least-privilege access across cloud identity services.
What to study next
Got this wrong? Here's your next step.
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
Network Design — This question tests Network Design — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: Internet gateway for public subnets and egress-only internet gateway for private subnets — Option D is correct because an egress-only internet gateway (EIGW) is the AWS-managed service designed specifically to provide outbound-only IPv6 access from private subnets to the internet, while an internet gateway (IGW) handles both inbound and outbound IPv4/IPv6 traffic for public subnets. Unlike a NAT gateway, which only supports IPv4, the EIGW works with IPv6 and prevents any inbound IPv6 connections from the internet, meeting the requirement for outbound-only IPv6 access.
What should I do if I get this ANS-C01 question wrong?
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
What is the key concept behind this question?
Read the scenario before looking for a memorised answer.
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Question Discussion
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