The correct answer is to add a route in the private subnet’s route table pointing to the gateway endpoint and to configure the endpoint policy to allow access to the specific S3 bucket. A Gateway Endpoint for S3 works by adding a prefix list route in the route table of the private subnet, directing S3 traffic directly to the endpoint without leaving the AWS network, which eliminates the need for a NAT gateway or public IP. On the AWS Certified Advanced Networking Specialty ANS-C01 exam, this question tests your understanding of how Gateway Endpoints differ from Interface Endpoints—specifically that they do not use ENIs or security groups, and they are free of charge. A common trap is assuming a NAT gateway is required for private subnet access, but the Gateway Endpoint itself provides the private, direct path. Memory tip: think “Gateway = Route Table route only; no ENI, no NAT.”
ANS-C01 Network Security, Compliance and Governance Practice Question
This ANS-C01 practice question tests your understanding of network security, compliance and governance. This is a configuration task: choose the command set that satisfies every stated requirement. Small differences — like 'secret' vs 'password' or 'transport input ssh' vs 'all' — change whether the answer is correct. 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 has a VPC with a CIDR of 10.0.0.0/16. The VPC contains a public subnet (10.0.1.0/24) and a private subnet (10.0.2.0/24). An EC2 instance in the private subnet needs to access an S3 bucket. The company wants to use a VPC endpoint for S3. Which TWO configurations are required?
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Create an endpoint policy that allows access to the S3 bucket.
Option A is correct because a gateway endpoint for S3 must have a route in the private subnet's route table pointing to the endpoint. Option C is correct because the endpoint policy must allow the instance to access the specific bucket. Option B is wrong because gateway endpoints do not use ENIs or security groups. Option D is wrong because gateway endpoints are free; no need to assign a public IP. Option E is wrong because NAT gateway is not needed when using a VPC endpoint.
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.
✗
Assign a public IP address to the EC2 instance.
Why it's wrong here
The instance is in a private subnet and does not need a public IP for S3 access via endpoint.
✓
Create an endpoint policy that allows access to the S3 bucket.
Why this is correct
The endpoint policy controls which resources can be accessed via the endpoint.
Gateway endpoints do not have security groups; they use endpoint policies.
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: Create an endpoint policy that allows access to the S3 bucket. — Option A is correct because a gateway endpoint for S3 must have a route in the private subnet's route table pointing to the endpoint. Option C is correct because the endpoint policy must allow the instance to access the specific bucket. Option B is wrong because gateway endpoints do not use ENIs or security groups. Option D is wrong because gateway endpoints are free; no need to assign a public IP. Option E is wrong because NAT gateway is not needed when using a VPC endpoint.
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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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.
Question Discussion
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