Quick Answer
The answer is a NAT gateway in a public subnet. This component enables EC2 instances in private subnets to initiate outbound internet access for tasks like downloading software patches, while keeping those instances unreachable from the internet. A NAT gateway, placed in a public subnet with an attached internet gateway, translates the private IPs of the instances to the gateway’s public IP, allowing outbound traffic and returning responses. On the AWS Certified SysOps Administrator Associate SOA-C02 exam, this scenario tests your understanding of VPC networking and common misconfigurations—a frequent trap is assuming an internet gateway alone provides private subnet access, which it does not, or confusing a NAT gateway with an egress-only internet gateway, which only supports IPv6. Remember the memory tip: “Private outbound? NAT in public inbound.”
This SOA-C02 practice question tests your understanding of reliability and business continuity. 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 company has an Auto Scaling group that launches EC2 instances in private subnets. The instances need to download software patches from the internet. Which component must be added to the VPC to allow outbound internet traffic while keeping the instances private?
An internet gateway attached to the VPC
Why wrong: Internet gateway by itself does not allow private instances.
A VPC peering connection to a VPC with internet access
Why wrong: VPC peering does not provide internet access.
An egress-only internet gateway
Why wrong: Egress-only IGW is for IPv6 only.
A NAT gateway in a public subnet
NAT gateway enables outbound internet for private instances.
Answer choices
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
A NAT gateway in a public subnet
Option A is correct because a NAT gateway in a public subnet allows instances in private subnets to initiate outbound traffic to the internet. Option B is wrong because internet gateway alone does not allow private instances to reach the internet. Option C is wrong because VPC peering does not provide internet access. Option D is wrong because an egress-only internet gateway is for IPv6 traffic.
Key principle: Count usable hosts — not total addresses — and remember that the network and broadcast addresses are not available to hosts in standard IPv4 subnets.
Answer analysis
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 by itself does not allow private instances.
A VPC peering connection to a VPC with internet access
Why it's wrong here
VPC peering does not provide internet access.
An egress-only internet gateway
Why it's wrong here
Egress-only IGW is for IPv6 only.
A NAT gateway in a public subnet
Common exam traps
Subnetting questions often tempt you into counting all addresses. In normal IPv4 subnets, the network and broadcast addresses are not usable host addresses.
Detailed technical explanation
Subnetting questions test whether you can identify the network, broadcast address, usable range, mask and correct subnet. Slow down enough to calculate the block size correctly.
Key takeaway
Count usable hosts — not total addresses — and remember that the network and broadcast addresses are not available to hosts in standard IPv4 subnets.
Real-world example
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
Review block sizes, usable host formulas (2^n − 2), and how to find network and broadcast addresses for /24 through /30. Then practise related SOA-C02 subnetting questions on CIDR, address ranges, and subnet selection.
Reliability and Business Continuity — study guide chapter
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FAQ
Reliability and Business Continuity — This question tests Reliability and Business Continuity — CIDR notation defines the prefix length..
The correct answer is: A NAT gateway in a public subnet — Option A is correct because a NAT gateway in a public subnet allows instances in private subnets to initiate outbound traffic to the internet. Option B is wrong because internet gateway alone does not allow private instances to reach the internet. Option C is wrong because VPC peering does not provide internet access. Option D is wrong because an egress-only internet gateway is for IPv6 traffic.
Review block sizes, usable host formulas (2^n − 2), and how to find network and broadcast addresses for /24 through /30. Then practise related SOA-C02 subnetting questions on CIDR, address ranges, and subnet selection.
CIDR notation defines the prefix length.
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Last reviewed: Jun 20, 2026
This SOA-C02 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 SOA-C02 exam.
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