The answer is to create Gateway Endpoints in each VPC that needs access, because VPC Gateway Endpoints are not transitive across VPCs. A Gateway Endpoint functions as a regional service that uses route table entries to direct traffic to AWS services like S3 or DynamoDB, but these routes are local to the VPC and are not propagated through a Transit Gateway. Since the Transit Gateway does not support transitive routing for Gateway Endpoints, other VPCs cannot reach the shared endpoint via the Transit Gateway alone; each VPC must have its own endpoint with the appropriate route table entries. On the AWS Certified Advanced Networking Specialty ANS-C01 exam, this tests your understanding of the distinction between Gateway Endpoints and Interface Endpoints, and the common trap is assuming that Transit Gateway can bridge endpoint connectivity. Remember the key rule: Gateway Endpoints are VPC-local and non-transitive—think of them as a private door for each house, not a shared hallway.
ANS-C01 Network Design Practice Question
This ANS-C01 practice question tests your understanding of network design. 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 multiple VPCs connected via AWS Transit Gateway. One VPC contains a shared services endpoint (e.g., Amazon S3) using a VPC Gateway Endpoint. How can other VPCs access this endpoint?
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Create Gateway Endpoints in each VPC that needs access
A VPC Gateway Endpoint is a regional service that uses route table entries to direct traffic to AWS services like S3 or DynamoDB without leaving the AWS network. Since Gateway Endpoints are not transitive across VPCs, each VPC that needs to access the shared S3 endpoint must have its own Gateway Endpoint created in that VPC, with the appropriate route table entries pointing to the endpoint. The Transit Gateway does not propagate Gateway Endpoint routes, so other VPCs cannot reach the endpoint through the Transit Gateway alone.
Key principle: Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
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 Gateway Endpoints in each VPC that needs access
Why this is correct
Each VPC must have its own Gateway Endpoint for S3.
Related concept
Read the scenario before looking for a memorised answer.
✗
Use AWS PrivateLink to access the S3 endpoint
Why it's wrong here
PrivateLink is for Interface Endpoints, not Gateway Endpoints.
✗
Configure Direct Connect to access the endpoint
Why it's wrong here
Direct Connect does not help with Gateway Endpoint access.
✗
Create a route in Transit Gateway pointing to the endpoint
Why it's wrong here
Transit Gateway cannot route to Gateway Endpoints.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates assume Transit Gateway can route traffic to a Gateway Endpoint in another VPC, but Gateway Endpoints are not transitive and cannot be used as a target in Transit Gateway route tables, requiring each VPC to have its own endpoint.
Detailed technical explanation
How to think about this question
Gateway Endpoints use prefix lists (e.g., com.amazonaws.us-east-1.s3) in VPC route tables to direct traffic to the AWS service, and these routes are not propagated to Transit Gateway attachments. This means each VPC must have its own Gateway Endpoint and the corresponding route table entries; otherwise, traffic from other VPCs will either traverse the internet or require a NAT gateway, defeating the purpose of private access. In real-world scenarios, organizations often centralize S3 access via a single VPC with a Gateway Endpoint and use VPC Peering or Transit Gateway with a proxy/NAT in that VPC, but the direct endpoint itself is not transitive.
KKey Concepts to Remember
Read the scenario before looking for a memorised answer.
Find the constraint that changes the correct option.
Eliminate answers that are true in general but not in this case.
TExam Day Tips
→Watch for words such as best, first, most likely and least administrative effort.
→Review why wrong options are wrong, not only why the correct option is correct.
Key takeaway
Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
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.
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
Network Design — This question tests Network Design — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: Create Gateway Endpoints in each VPC that needs access — A VPC Gateway Endpoint is a regional service that uses route table entries to direct traffic to AWS services like S3 or DynamoDB without leaving the AWS network. Since Gateway Endpoints are not transitive across VPCs, each VPC that needs to access the shared S3 endpoint must have its own Gateway Endpoint created in that VPC, with the appropriate route table entries pointing to the endpoint. The Transit Gateway does not propagate Gateway Endpoint routes, so other VPCs cannot reach the endpoint through the Transit Gateway alone.
What should I do if I get this ANS-C01 question wrong?
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
What is the key concept behind this question?
Read the scenario before looking for a memorised answer.
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Question Discussion
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