The answer is to add a NAT Gateway in the PublicSubnet and update the PrivateSubnet’s route table to point to it. This is correct because a NAT Gateway, placed in a public subnet with an Internet Gateway attached, allows instances in a private subnet to initiate outbound traffic to the internet for tasks like software updates while blocking unsolicited inbound connections. The private subnet’s route table must have a default route (0.0.0.0/0) targeting the NAT Gateway, which then routes traffic through the Internet Gateway. On the AWS Certified Solutions Architect Professional SAP-C02 exam, this scenario tests your understanding of the standard pattern for enabling internet access from private subnets without exposing instances to inbound traffic. A common trap is confusing a NAT Gateway with a NAT Instance or forgetting to update the route table; the exam often presents a CloudFormation template missing this route. Memory tip: “Private out, NAT about” — the NAT Gateway lives in a public subnet to translate private IPs for outbound-only internet access.
SAP-C02 Design for New Solutions Practice Question
This SAP-C02 practice question tests your understanding of design for new solutions. 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 deployed the above CloudFormation template. An EC2 instance launched in the PrivateSubnet needs to access the internet for software updates. Which action is required?
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Add a NAT Gateway in the PublicSubnet and update the PrivateSubnet's route table to point to the NAT Gateway
A NAT Gateway placed in a public subnet with an Internet Gateway attached allows instances in private subnets to initiate outbound traffic to the internet (e.g., for software updates) while preventing inbound connections from the internet. The private subnet's route table must have a default route (0.0.0.0/0) pointing to the NAT Gateway. This is the standard AWS pattern for outbound-only internet access from private subnets.
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.
✗
Create a VPC Peering connection to a public VPC
Why it's wrong here
Peering does not provide internet access.
✓
Add a NAT Gateway in the PublicSubnet and update the PrivateSubnet's route table to point to the NAT Gateway
Why this is correct
NATGateway enables outbound internet for private instances.
Related concept
Read the scenario before looking for a memorised answer.
✗
Add an Internet Gateway to the VPC and route the private subnet's route table to it
Why it's wrong here
IGW alone does not provide internet access to private instances.
✗
Modify the PrivateSubnet to assign public IP addresses on launch
Why it's wrong here
Public IP alone does not provide internet access; needs IGW.
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, thinking that routing a private subnet directly to an Internet Gateway is sufficient, but this would expose instances to inbound traffic and require public IPs, defeating the purpose of a private subnet.
Detailed technical explanation
How to think about this question
A NATGateway uses Elastic IPs and resides in a public subnet with a route to an Internet Gateway. It performs source network address translation (SNAT), replacing the private IP of the instance with the NAT Gateway's Elastic IP for outbound traffic. Responses are mapped back to the private instance via connection tracking. This design ensures that private instances remain unreachable from the internet while still being able to fetch updates or patches.
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.
Design for New Solutions — This question tests Design for New Solutions — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: Add a NAT Gateway in the PublicSubnet and update the PrivateSubnet's route table to point to the NAT Gateway — A NAT Gateway placed in a public subnet with an Internet Gateway attached allows instances in private subnets to initiate outbound traffic to the internet (e.g., for software updates) while preventing inbound connections from the internet. The private subnet's route table must have a default route (0.0.0.0/0) pointing to the NAT Gateway. This is the standard AWS pattern for outbound-only internet access from private subnets.
What should I do if I get this SAP-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.
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Question Discussion
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