- A
Create a NAT Gateway in a public subnet and update the private subnet route table to use it
Why wrong: NAT Gateway is a managed service that is easier to set up, but it incurs higher hourly and data processing costs compared to a NAT instance.
- B
Launch a NAT instance in a public subnet with an Elastic IP and disable source/destination check, then update private subnet route tables
A NAT instance costs less per hour than a NAT Gateway, making it the more cost-effective option when minimizing costs is the primary goal.
- C
Attach an Internet Gateway to the VPC and add a default route to the Internet Gateway in the private subnets
Why wrong: An Internet Gateway alone does not allow private subnets to initiate outbound traffic; a NAT device is required.
- D
Use AWS Transit Gateway with a VPN connection to an on-premises data center for internet access
Why wrong: Transit Gateway with VPN is more complex and expensive, and it would route traffic on-premises even for internet access, which is inefficient.
Quick Answer
The answer is to launch a NAT instance in a public subnet with an Elastic IP and disable source/destination check, then update the private subnet route tables. This is correct because a NAT instance acts as a cost-effective NAT instance for private subnet outbound internet, routing traffic from private subnets to the internet while blocking unsolicited inbound connections, and disabling source/destination check allows the instance to forward packets not destined for itself. On the AWS Certified SysOps Administrator Associate SOA-C02 exam, this scenario tests your ability to balance functionality with cost optimization, often contrasting the cheaper NAT instance against the fully managed but pricier NAT Gateway. A common trap is forgetting to disable source/destination check, which would break routing. Memory tip: think “NAT instance = DIY savings; disable Src/Dest check or no internet for your private subnet.”
SOA-C02 Networking and Content Delivery Practice Question
This SOA-C02 practice question tests your understanding of networking and content delivery. 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 a VPC with public and private subnets. The private subnets need outbound internet access to download software updates while preventing any inbound internet traffic. The SysOps administrator must minimize costs. Which solution should the administrator implement?
Clue words in this question
Noticing these words before you look at the options changes how you read each choice.
Clue:
"minimum / minimize"Why it matters: Asks for the least resource use — fewest addresses, smallest subnet, lowest overhead. Eliminate over-provisioned options even if they would technically work.
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
Launch a NAT instance in a public subnet with an Elastic IP and disable source/destination check, then update private subnet route tables
Option B is correct because a NAT instance, when launched in a public subnet with an Elastic IP and source/destination check disabled, can route outbound traffic from private subnets to the internet while blocking unsolicited inbound connections. This solution minimizes costs compared to a NAT Gateway, as NAT instances use existing EC2 instance pricing and can be further reduced with spot instances or smaller instance types.
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 NAT Gateway in a public subnet and update the private subnet route table to use it
- ✓
Launch a NAT instance in a public subnet with an Elastic IP and disable source/destination check, then update private subnet route tables
Why this is correct
A NAT instance costs less per hour than a NAT Gateway, making it the more cost-effective option when minimizing costs is the primary goal.
Clue confirmation
The clue word "minimum / minimize" in the question point toward this answer.
Related concept
Read the scenario before looking for a memorised answer.
- ✗
Attach an Internet Gateway to the VPC and add a default route to the Internet Gateway in the private subnets
- ✗
Use AWS Transit Gateway with a VPN connection to an on-premises data center for internet access
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates often choose the NAT Gateway (Option A) because it is fully managed and simpler, overlooking the explicit cost-minimization requirement that favors the cheaper, self-managed NAT instance.
Detailed technical explanation
How to think about this question
A NAT instance operates at the network layer (Layer 3) by performing IP masquerading (source NAT) using iptables rules, typically with a script that configures IP forwarding and masquerading. Disabling the source/destination check on the instance's ENI is critical because, by default, AWS drops traffic where the instance is not the source or destination; without this, the NAT instance cannot forward packets between subnets. In a real-world scenario, a NAT instance can be placed in an Auto Scaling group with a lifecycle hook to ensure high availability, but for cost minimization, a single small instance (e.g., t4g.nano) suffices for low-volume update traffic.
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 startup's cloud architect reviews their monthly bill and notices costs are higher than expected for a long-running batch job. Switching from on-demand instances to Reserved Instances — or using Spot/Preemptible VMs — can reduce compute costs by up to 72 %. Questions like this test whether you understand the tradeoffs between commitment, flexibility, and cost across cloud pricing models.
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.
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FAQ
Questions learners often ask
What does this SOA-C02 question test?
Networking and Content Delivery — This question tests Networking and Content Delivery — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: Launch a NAT instance in a public subnet with an Elastic IP and disable source/destination check, then update private subnet route tables — Option B is correct because a NAT instance, when launched in a public subnet with an Elastic IP and source/destination check disabled, can route outbound traffic from private subnets to the internet while blocking unsolicited inbound connections. This solution minimizes costs compared to a NAT Gateway, as NAT instances use existing EC2 instance pricing and can be further reduced with spot instances or smaller instance types.
What should I do if I get this SOA-C02 question wrong?
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
Are there clue words in this question I should notice?
Yes — watch for: "minimum / minimize". Asks for the least resource use — fewest addresses, smallest subnet, lowest overhead. Eliminate over-provisioned options even if they would technically work.
What is the key concept behind this question?
Read the scenario before looking for a memorised answer.
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Last reviewed: Jun 11, 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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