The answer is to add a route in the private subnet’s route table pointing to the S3 gateway endpoint. A VPC Gateway Endpoint for S3 works by adding a specific route to the endpoint’s prefix list in the route table of the subnet where the resource resides; without this route, traffic from the private subnet to S3 has no path and will fail, even though the endpoint is attached to the VPC. On the AWS Certified SysOps Administrator Associate SOA-C02 exam, this scenario tests your understanding that gateway endpoints are not automatically associated with subnets—you must explicitly update the route table, which is a common trap for those who assume attaching the endpoint is enough. A frequent memory tip is to think of the endpoint as a “door” that needs a “hallway” (the route) from the subnet to reach it. Remember: endpoint attached ≠ endpoint routed.
SOA-C02 Networking and Content Delivery Practice Question
This SOA-C02 practice question tests your understanding of networking and content delivery. The scenario asks you to isolate a root cause — eliminate options that address a different problem before choosing. 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 block of 10.0.0.0/16. They have two subnets: 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 to store logs. The instance currently has no internet access. The SysOps administrator has created a VPC endpoint for S3 (gateway type) and attached it to the VPC. The instance still cannot reach S3. What additional step is required?
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Add a route in the private subnet's route table pointing to the S3 endpoint
Option A is correct because the route table for the private subnet must have a route to the S3 endpoint (prefix list). Option B is wrong because S3 endpoints do not require internet access. Option C is wrong because the endpoint policy is not the issue if it allows all actions. Option D is wrong because the instance's security group does not block traffic to S3 by default.
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 add a route to it
Why it's wrong here
Gateway endpoints do not use IGW; they work within the VPC.
✗
Add a security group rule to allow outbound HTTPS traffic to S3
Why it's wrong here
Security groups are stateful and allow outbound traffic by default.
✗
Modify the endpoint policy to allow all S3 actions
Why it's wrong here
The default policy allows all; policy is not blocking.
✓
Add a route in the private subnet's route table pointing to the S3 endpoint
Why this is correct
The endpoint uses a prefix list, and the route table must have a route for S3 traffic to go through the endpoint.
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 SOA-C02 subnetting questions on CIDR, address ranges, and subnet selection.
Networking and Content Delivery — This question tests Networking and Content Delivery — CIDR notation defines the prefix length..
What is the correct answer to this question?
The correct answer is: Add a route in the private subnet's route table pointing to the S3 endpoint — Option A is correct because the route table for the private subnet must have a route to the S3 endpoint (prefix list). Option B is wrong because S3 endpoints do not require internet access. Option C is wrong because the endpoint policy is not the issue if it allows all actions. Option D is wrong because the instance's security group does not block traffic to S3 by default.
What should I do if I get this SOA-C02 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 SOA-C02 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 →
Share a tip, memory trick, or ask about the reasoning behind this question. Do not post real exam questions, leaked content, braindumps, or copyrighted exam material. Comments are moderated and may be removed without notice.
This SOA-C02 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 SOA-C02 exam.
Question Discussion
Share a tip, memory trick, or ask about the reasoning behind this question. Do not post real exam questions, leaked content, braindumps, or copyrighted exam material. Comments are moderated and may be removed without notice.
Sign in to join the discussion.