The answer is a NAT gateway in a public subnet, an internet gateway, and a route table in the private subnet with a default route pointing to the NAT gateway. This combination works because the NAT gateway, residing in a public subnet with an internet gateway attached, translates private IP addresses to its own public IP for outbound traffic, while the private subnet’s route table ensures all non-local traffic is forwarded to the NAT device. On the AWS Certified Security Specialty SCS-C02 exam, this scenario tests your understanding of how to enable outbound internet for private subnets without granting direct inbound access—a common requirement for secure database tiers. A frequent trap is confusing a VPC gateway endpoint (for S3 or DynamoDB) with general internet access, or assuming a NAT gateway alone suffices without the internet gateway. Remember the three-part chain: internet gateway → NAT gateway → private route table default route.
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 private subnets will host databases that should not have direct internet access. Which three components are required to provide outbound internet access for these databases? (Choose THREE.)
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
An internet gateway attached to the VPC.
Options A, B, and E are correct. A NAT gateway or NAT instance in a public subnet provides outbound internet access. Route tables in private subnets must have a default route pointing to the NAT device. An internet gateway is needed to provide internet connectivity to the public subnet. Option C is wrong because a VPC gateway endpoint is for S3/DynamoDB, not general internet. Option D is wrong because AWS WAF is a web application firewall.
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.
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 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.
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: An internet gateway attached to the VPC. — Options A, B, and E are correct. A NAT gateway or NAT instance in a public subnet provides outbound internet access. Route tables in private subnets must have a default route pointing to the NAT device. An internet gateway is needed to provide internet connectivity to the public subnet. Option C is wrong because a VPC gateway endpoint is for S3/DynamoDB, not general internet. Option D is wrong because AWS WAF is a web application firewall.
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.
What is the key concept behind this question?
CIDR notation defines the prefix length.
About these practice questions
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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 designing a VPC with public and private subnets. The private subnets must be able to download software updates from the internet. Which TWO components can provide this functionality without exposing the private instances to inbound internet traffic?
medium
✓ A.NAT gateway
B.Internet gateway
C.VPC endpoint
D.Egress-only internet gateway
✓ E.NAT instance
Why A: Option A (NAT gateway) and Option C (NAT instance) are correct because they allow outbound traffic to the internet and block unsolicited inbound traffic. Option B is wrong because an internet gateway allows bidirectional traffic. Option D (egress-only internet gateway) is for IPv6. Option E (VPC endpoint) is for AWS services, not general internet.
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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.
Question Discussion
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