This ANS-C01 practice question tests your understanding of network implementation. 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 is deploying a new VPC with public and private subnets. The VPC will host web servers in the public subnet and database servers in the private subnet. The web servers need to access the internet for updates, and the database servers need to receive traffic only from the web servers. Which THREE components are essential for this architecture?
NAT gateway in the public subnet
Allows private instances to access internet.
Network ACL for subnets
Why wrong: Optional; security groups are more appropriate.
Internet gateway
Required for public subnet internet access.
VPC endpoint for S3
Why wrong: Not required for internet access.
Security groups for web and database servers
Controls traffic between tiers.
Answer choices
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
NAT gateway in the public subnet
Options A, C, and D are correct because an internet gateway provides internet access for public subnets, a NAT gateway provides internet access for private subnets, and security groups act as firewalls for EC2 instances. Option B is wrong because NACLs are stateless and less granular. Option E is wrong because VPC endpoint is not needed for general internet access.
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
For each option: why learners choose it and why it is or isn't the right answer here.
NAT gateway in the public subnet
Why this is correct
Allows private instances to access internet.
Related concept
CIDR notation defines the prefix length.
Network ACL for subnets
Why it's wrong here
Optional; security groups are more appropriate.
Internet gateway
Why this is correct
Required for public subnet internet access.
Related concept
CIDR notation defines the prefix length.
VPC endpoint for S3
Why it's wrong here
Not required for internet access.
Security groups for web and database servers
Why this is correct
Controls traffic between tiers.
Related concept
CIDR notation defines the prefix length.
Common exam traps
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
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.
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
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
Review block sizes, usable host formulas (2^n − 2), and how to find network and broadcast addresses for /24 through /30. Then practise related ANS-C01 subnetting questions on CIDR, address ranges, and subnet selection.
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FAQ
Network Implementation — This question tests Network Implementation — CIDR notation defines the prefix length..
The correct answer is: NAT gateway in the public subnet — Options A, C, and D are correct because an internet gateway provides internet access for public subnets, a NAT gateway provides internet access for private subnets, and security groups act as firewalls for EC2 instances. Option B is wrong because NACLs are stateless and less granular. Option E is wrong because VPC endpoint is not needed for general internet access.
Review block sizes, usable host formulas (2^n − 2), and how to find network and broadcast addresses for /24 through /30. Then practise related ANS-C01 subnetting questions on CIDR, address ranges, and subnet selection.
CIDR notation defines the prefix length.
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Last reviewed: Jun 20, 2026
This ANS-C01 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 ANS-C01 exam.
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