The answer is deploying a NAT gateway in a public subnet. This satisfies the requirement because a NAT gateway, placed in a public subnet with an Elastic IP and a route to an internet gateway, allows instances in private subnets to initiate outbound internet connections—such as for software updates—while the gateway’s stateful firewall automatically drops any unsolicited inbound traffic from the internet. The private subnet’s route table must have a default route (0.0.0.0/0) pointing to the NAT gateway’s private IP to forward outbound traffic. On the AWS Certified Security Specialty SCS-C02 exam, this scenario tests your understanding of how to enable outbound internet from private subnets using NAT gateway without exposing resources to inbound attacks. A common trap is confusing a NAT gateway with a NAT instance or assuming a public subnet is required for the private instances themselves. Memory tip: think “NAT out, never in”—the gateway only translates outbound requests, never unsolicited inbound ones.
SCS-C02 Infrastructure Security Practice Question
This SCS-C02 practice question tests your understanding of infrastructure security. 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 security engineer is designing a VPC with public and private subnets. The application servers in the private subnets need to access the internet for software updates, but must not be directly reachable from the internet. Which TWO actions satisfy these requirements?
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Add a route in the private subnet's route table pointing to the NAT gateway.
Option B is correct because a NAT gateway, when deployed in a public subnet with an associated Elastic IP and a route to an internet gateway, allows instances in private subnets to initiate outbound connections to the internet (e.g., for software updates) while preventing any unsolicited inbound connections from the internet. The private subnet's route table must include a default route (0.0.0.0/0) pointing to the NAT gateway's private IP address to forward outbound traffic through it.
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.
✗
Configure the private subnet's security group to allow inbound traffic from 0.0.0.0/0.
Why it's wrong here
Incorrect: This would allow inbound internet traffic directly to instances.
✓
Add a route in the private subnet's route table pointing to the NAT gateway.
Why this is correct
Correct: This routes outbound internet traffic through the NATgateway.
Related concept
Read the scenario before looking for a memorised answer.
✗
Attach an internet gateway to the private subnet's route table.
Why it's wrong here
Incorrect: This would make the private subnet public, allowing inbound traffic.
✗
Create a VPC gateway endpoint for Amazon S3.
Why it's wrong here
Incorrect: VPC endpoints provide access to specific AWS services, not general internet.
✓
Deploy a NAT gateway in a public subnet.
Why this is correct
Correct: NATgateway enables outbound internet access from 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
The trap here is that candidates often confuse a NATgateway with an internet gateway, mistakenly thinking that adding an internet gateway to a private subnet's route table provides outbound-only access, when in fact it enables bidirectional internet connectivity and requires public IPs on the instances.
Detailed technical explanation
How to think about this question
A NAT gateway operates at Layer 4 (TCP/UDP) and performs source network address translation (SNAT), rewriting the source IP of outbound packets to its own Elastic IP address and tracking connection state so that return traffic is forwarded back to the private instance. Unlike a NAT instance, a NAT gateway is a managed service that automatically scales up to 45 Gbps and does not require patching or failover scripts. In real-world scenarios, if the NAT gateway is placed in a public subnet without a route to an internet gateway, outbound traffic will fail; the public subnet must have a default route pointing to an internet gateway for the NAT gateway to function.
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 media company stores terabytes of video archives that are accessed once a year for audit purposes. Moving these objects to a cold storage tier (Azure Archive, S3 Glacier, or Google Nearline) costs a fraction of hot storage. Questions like this test whether you understand storage tiers, access frequency tradeoffs, and retrieval latency requirements.
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.
Infrastructure Security — This question tests Infrastructure Security — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: Add a route in the private subnet's route table pointing to the NAT gateway. — Option B is correct because a NAT gateway, when deployed in a public subnet with an associated Elastic IP and a route to an internet gateway, allows instances in private subnets to initiate outbound connections to the internet (e.g., for software updates) while preventing any unsolicited inbound connections from the internet. The private subnet's route table must include a default route (0.0.0.0/0) pointing to the NAT gateway's private IP address to forward outbound traffic through it.
What should I do if I get this SCS-C02 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.
About these practice questions
Courseiva creates original exam-style practice questions with explanations and wrong-answer analysis. It does not publish real exam questions, exam dumps, or protected exam content. Learn why practice questions differ from exam dumps →
These questions test the same concept from different angles. Work through them to make sure you can recognise it however the exam phrases it.
Variation 1. A security engineer is configuring a new VPC with public and private subnets. The application servers in the private subnet need to download patches from the internet. Which component is required?
easy
A.VPC endpoint
B.Direct Connect
C.Internet gateway
✓ D.NAT gateway
Why D: A NAT gateway or NAT instance in a public subnet allows instances in private subnets to initiate outbound traffic to the internet and receive responses. Internet gateway alone is for public subnets. VPC endpoints are for specific services, not general internet access.
Last reviewed: Jun 11, 2026
Question Discussion
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This SCS-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 SCS-C02 exam.
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