This SCS-C02 practice question tests your understanding of infrastructure security. The scenario asks you to isolate a root cause — eliminate options that address a different problem before choosing. 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 a public subnet and a private subnet. An EC2 instance in the private subnet needs to download patches from the internet. The company wants to minimize costs and avoid NAT Gateway or NAT Instance charges. Which solution should be used?
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 the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Create a VPC Gateway Endpoint for S3 and configure the instance to download patches from S3.
Option C is correct because a VPC Gateway Endpoint is used for S3 and DynamoDB, not for general internet access. For general internet access, a NAT device is required. However, if the patches are hosted on S3, a Gateway Endpoint is free. Option A is wrong because an internet gateway alone cannot be used from private subnets. Option B is wrong because an egress-only internet gateway is for IPv6. Option D is wrong because a proxy instance incurs costs.
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
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
✗
Deploy a proxy instance in a public subnet and configure the private instance to use the proxy.
Why it's wrong here
This incurs costs for the proxy instance.
✗
Use an egress-only internet gateway for the private subnet.
Why it's wrong here
Egress-only internet gateways support IPv6 only.
✗
Attach an internet gateway to the VPC and add a route to the private subnet route table pointing to the internet gateway.
Why it's wrong here
Private subnets cannot route to an internet gateway directly.
✓
Create a VPC Gateway Endpoint for S3 and configure the instance to download patches from S3.
Why this is correct
Gateway Endpoints are free and allow access to S3 from private subnets.
Clue confirmation
The clue word "minimum / minimize" in the question point toward this answer.
Common exam trap: usable hosts are not the same as total addresses
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
How to think about this question
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.
KKey Concepts to Remember
CIDR notation defines the prefix length.
Block size helps identify subnet boundaries.
Network and broadcast addresses are not usable hosts in normal IPv4 subnets.
The required host count determines the smallest suitable subnet.
TExam Day Tips
→Write the block size before choosing the subnet.
→Check whether the question asks for hosts, subnets or a specific address range.
→Do not confuse /24, /25, /26 and /27 host counts.
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
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.
Review block sizes, usable host formulas (2^n − 2), and how to find network and broadcast addresses for /24 through /30. Then practise related SCS-C02 subnetting questions on CIDR, address ranges, and subnet selection.
Infrastructure Security — This question tests Infrastructure Security — CIDR notation defines the prefix length..
What is the correct answer to this question?
The correct answer is: Create a VPC Gateway Endpoint for S3 and configure the instance to download patches from S3. — Option C is correct because a VPC Gateway Endpoint is used for S3 and DynamoDB, not for general internet access. For general internet access, a NAT device is required. However, if the patches are hosted on S3, a Gateway Endpoint is free. Option A is wrong because an internet gateway alone cannot be used from private subnets. Option B is wrong because an egress-only internet gateway is for IPv6. Option D is wrong because a proxy instance incurs costs.
What should I do if I get this SCS-C02 question wrong?
Review block sizes, usable host formulas (2^n − 2), and how to find network and broadcast addresses for /24 through /30. Then practise related SCS-C02 subnetting questions on CIDR, address ranges, and subnet selection.
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?
CIDR notation defines the prefix length.
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