The correct answer is a route table for private subnets with a 0.0.0.0/0 destination pointing to a NAT Gateway, along with the NAT Gateway itself placed in a public subnet. This design works because the NAT Gateway, which resides in a public subnet with an Elastic IP, translates private instance traffic to the public internet while blocking any unsolicited inbound connections, ensuring the private subnets remain unreachable from the internet. On the AWS Certified Advanced Networking Specialty ANS-C01 exam, this question tests your understanding of VPC routing and NAT architecture, often appearing as a foundational scenario for hybrid or multi-tier network designs. A common trap is confusing the Internet Gateway with the NAT Gateway—remember that an Internet Gateway alone requires public IPs on instances, which would expose them directly. Another pitfall is selecting Security Groups, which are stateful firewalls and not routing components. For a quick memory tip: think “NAT in public, route in private” to recall that the NAT Gateway lives in the public subnet while the private subnet’s default route points to it.
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. The private subnets must have outbound internet access for software updates, but must not be directly reachable from the internet. Which two components are required for this design? (Choose two.)
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 a public subnet
Options B and E are correct. A NATGateway in a public subnet allows instances in private subnets to initiate outbound traffic to the internet, while the private subnets route 0.0.0.0/0 traffic to the NAT Gateway. Option A is wrong because an Internet Gateway alone does not provide outbound-only access; instances would need public IPs. Option C is wrong because Security Groups are firewalls, not for internet access. Option D is wrong because a VPN connection is for private connectivity, not 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
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
✓
NAT Gateway in a public subnet
Why this is correct
NATGateway enables outbound internet access for private instances.
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.
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: NAT Gateway in a public subnet — Options B and E are correct. A NAT Gateway in a public subnet allows instances in private subnets to initiate outbound traffic to the internet, while the private subnets route 0.0.0.0/0 traffic to the NAT Gateway. Option A is wrong because an Internet Gateway alone does not provide outbound-only access; instances would need public IPs. Option C is wrong because Security Groups are firewalls, not for internet access. Option D is wrong because a VPN connection is for private connectivity, not internet access.
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.
About these practice questions
Courseiva creates original exam-style practice questions with explanations and wrong-answer analysis. It does not publish real exam questions, exam dumps, or protected exam content. Learn why practice questions differ from exam dumps →
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 company is designing a VPC with public and private subnets. The private subnets need to access the internet for software updates but must not be directly accessible from the internet. Which AWS service should be used to provide internet access to instances in the private subnets?
easy
A.Internet gateway
✓ B.NAT gateway
C.VPC endpoint
D.Transit gateway
Why B: Option B is correct because a NAT gateway allows instances in private subnets to initiate outbound traffic to the internet but prevents inbound traffic from the internet. Option A is wrong because an internet gateway is for public subnets and allows inbound connections. Option C is wrong because a transit gateway connects VPCs but does not provide internet access. Option D is wrong because a VPC endpoint is for accessing AWS services privately, not the internet.
Variation 2. A company is designing a VPC with a public subnet for a web server and a private subnet for a database. The web server needs to download patches from the internet. The database should not have direct internet access. Which architecture meets these requirements?
easy
A.Place the web server in the public subnet with an Internet Gateway, and the database in the private subnet without any internet access.
B.Place both instances in the public subnet and use security groups to restrict inbound access to the database.
✓ C.Place the web server in the public subnet with an Internet Gateway, and the database in the private subnet with a route to a NAT Gateway in the public subnet for outbound access only.
D.Place the web server in the private subnet with a NAT Gateway, and the database in the public subnet with an Internet Gateway.
Why C: Option B is correct. A NAT Gateway in the public subnet allows the web server (in the same public subnet) to access the internet via its public IP or via the NAT Gateway if it's actually in a private subnet. However, the web server is in a public subnet, so it can have a public IP and access the internet directly. The database in the private subnet can use the NAT Gateway for outbound access if needed, but the question says database should not have direct internet access, so it should not have a public IP. Option A is wrong because an Internet Gateway alone does not provide outbound access for private instances. Option C is wrong because a VPN is not needed. Option D is wrong because a NAT Instance is not recommended; NAT Gateway is managed.
Last reviewed: Jun 20, 2026
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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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