The answer is to place web servers in public subnets with an internet gateway and database servers in private subnets with no direct internet access. This design is correct because a multi-tier VPC architecture with public and private subnets isolates the presentation tier from the data tier, ensuring that only the web layer receives inbound traffic from the internet while the database layer remains unreachable from outside the VPC. On the AWS Certified Advanced Networking Specialty ANS-C01 exam, this scenario tests your understanding of subnet routing and security group boundaries, often appearing as a foundational question that distinguishes between public-facing and internal resources. A common trap is assuming a NAT gateway provides inbound access—it only enables outbound traffic from private subnets, not inbound. Another pitfall is placing databases in public subnets, which directly exposes them to the internet. Memory tip: think of the internet gateway as a front door for web servers only, and private subnets as a locked vault for databases—no direct path in, only out if needed.
ANS-C01 Network Security, Compliance and Governance Practice Question
This ANS-C01 practice question tests your understanding of network security, compliance and governance. 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 multi-tier application in a VPC. The web servers must be accessible from the internet, but the database servers must not be. Which architecture meets these requirements?
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Place web servers in public subnets with an internet gateway, and databases in private subnets with no direct internet access.
Option B is correct: public subnets for web servers with internet gateway, private subnets for databases with no direct internet access. Option A is wrong because placing databases in public subnets exposes them. Option C is wrong because NAT gateway allows outbound only, not inbound. Option D is wrong because private subnets with NAT still allow outbound, but the question is about inbound.
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.
✗
Use a NAT gateway for the database servers to allow inbound traffic.
Place all servers in private subnets and use an AWS Site-to-Site VPN for internet access.
Why it's wrong here
VPN is for on-premises, not direct internet access.
✗
Place both web and database servers in public subnets and use security groups to restrict database access.
Why it's wrong here
Databases in public subnets are exposed to the internet.
Common exam traps
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 ANS-C01 subnetting questions on CIDR, address ranges, and subnet selection.
Network Security, Compliance and Governance — This question tests Network Security, Compliance and Governance — CIDR notation defines the prefix length..
What is the correct answer to this question?
The correct answer is: Place web servers in public subnets with an internet gateway, and databases in private subnets with no direct internet access. — Option B is correct: public subnets for web servers with internet gateway, private subnets for databases with no direct internet access. Option A is wrong because placing databases in public subnets exposes them. Option C is wrong because NAT gateway allows outbound only, not inbound. Option D is wrong because private subnets with NAT still allow outbound, but the question is about inbound.
What should I do if I get this ANS-C01 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 ANS-C01 subnetting questions on CIDR, address ranges, and subnet selection.
What is the key concept behind this question?
CIDR notation defines the prefix length.
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Question Discussion
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