The correct answer is to deploy a NAT Gateway in a public subnet and update the private subnet route table to point 0.0.0.0/0 to the NAT Gateway, combined with a VPC endpoint for S3 for private bucket access. This works because the NAT Gateway, residing in a public subnet with an Elastic IP, translates private instance traffic for outbound internet connectivity while preventing any inbound connections, thus keeping EC2 instances private. On the AWS Certified Advanced Networking Specialty ANS-C01 exam, this scenario tests your understanding of how to architect outbound internet access without public IPs, often appearing as a trap where candidates mistakenly choose an Internet Gateway (which requires a public IP on the instance) or a VPN/Direct Connect (which are for private hybrid connectivity, not general internet access). A key memory tip: remember that a NAT Gateway is for *outbound-only* internet from private subnets, while VPC endpoints are for *private* access to AWS services like S3 without traversing the internet.
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 solutions architect is designing a VPC with public and private subnets. The application in the private subnet needs to download patches from the internet. Which TWO options allow outbound internet access while keeping the EC2 instance in the private subnet without a public IP address?
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Create a VPC endpoint for Amazon S3 and update the route table.
Options A and D are correct. A NATGateway in a public subnet allows instances in private subnets to initiate outbound traffic to the internet. A VPC endpoint for S3 allows private access to S3 buckets. Option B (Internet Gateway) requires a public IP. Option C (Direct Connect) is for dedicated private connections. Option E (VPN) is for hybrid connectivity.
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.
✗
Attach an Internet Gateway to the VPC and assign a public IP to the instance.
Why it's wrong here
This would give the instance a public IP, which is not desired.
✗
Set up a Direct Connect connection to an on-premises data center.
Why it's wrong here
Direct Connect is for private connectivity, not general internet access.
✓
Create a VPC endpoint for Amazon S3 and update the route table.
Why this is correct
VPC endpoint allows private access to S3 without internet.
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 Design — This question tests Network Design — CIDR notation defines the prefix length..
What is the correct answer to this question?
The correct answer is: Create a VPC endpoint for Amazon S3 and update the route table. — Options A and D are correct. A NAT Gateway in a public subnet allows instances in private subnets to initiate outbound traffic to the internet. A VPC endpoint for S3 allows private access to S3 buckets. Option B (Internet Gateway) requires a public IP. Option C (Direct Connect) is for dedicated private connections. Option E (VPN) is for hybrid connectivity.
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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