- A
Create a VPC Peering connection between the public and private subnets.
Why wrong: VPC Peering connects different VPCs, not subnets within the same VPC.
- B
Attach a NAT Gateway in a public subnet and update the route table of the private subnets to point to the NAT Gateway for outbound traffic.
A NAT Gateway allows private instances to initiate outbound traffic to the internet but blocks inbound traffic from the internet, meeting the security requirement.
- C
Attach an Internet Gateway to the VPC and update the route table of the private subnets to point to the Internet Gateway.
Why wrong: An Internet Gateway allows inbound and outbound internet access, which would expose the databases to the internet.
- D
Attach a Virtual Private Gateway to the VPC and update the route table of the private subnets.
Why wrong: A Virtual Private Gateway is used for VPN connections to on-premises networks, not for internet access.
ANS-C01 Network Design Practice Question
This ANS-C01 practice question tests your understanding of network design. 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 designing a VPC with public and private subnets in two Availability Zones. The private subnets host databases that must be accessible only from the application servers in the public subnets. Which VPC feature should be used to allow the application servers to access the databases while preventing direct internet access to the databases?
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
Attach a NAT Gateway in a public subnet and update the route table of the private subnets to point to the NAT Gateway for outbound traffic.
Option B is correct because a NAT Gateway allows instances in private subnets to initiate outbound traffic to the internet, but it does not allow inbound traffic from the internet, which aligns with the requirement. Option A is wrong because an Internet Gateway would allow inbound traffic from the internet. Option C is wrong because a VPC Peering connection is used for connecting VPCs. Option D is wrong because a Virtual Private Gateway is used for VPN connections.
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.
- ✗
Create a VPC Peering connection between the public and private subnets.
Why it's wrong here
VPC Peering connects different VPCs, not subnets within the same VPC.
- ✓
Attach a NAT Gateway in a public subnet and update the route table of the private subnets to point to the NAT Gateway for outbound traffic.
- ✗
Attach an Internet Gateway to the VPC and update the route table of the private subnets to point to the Internet Gateway.
Why it's wrong here
An Internet Gateway allows inbound and outbound internet access, which would expose the databases to the internet.
- ✗
Attach a Virtual Private Gateway to the VPC and update the route table of the private subnets.
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 company's IT admin needs to give a contractor read-only access to production logs without sharing account credentials. Using role-based access control (RBAC) and temporary scoped permissions — not a permanent shared password — is the correct pattern. Questions like this test whether you can apply least-privilege access across cloud identity services.
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.
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FAQ
Questions learners often ask
What does this ANS-C01 question test?
Network Design — This question tests Network Design — CIDR notation defines the prefix length..
What is the correct answer to this question?
The correct answer is: Attach a NAT Gateway in a public subnet and update the route table of the private subnets to point to the NAT Gateway for outbound traffic. — Option B is correct because a NAT Gateway allows instances in private subnets to initiate outbound traffic to the internet, but it does not allow inbound traffic from the internet, which aligns with the requirement. Option A is wrong because an Internet Gateway would allow inbound traffic from the internet. Option C is wrong because a VPC Peering connection is used for connecting VPCs. Option D is wrong because a Virtual Private Gateway is used for VPN connections.
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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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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