ANS-C01 Network Design Practice Question
A company has a VPC with a CIDR of 10.0.0.0/16 and uses AWS Direct Connect with a private VIF to connect to on-premises. The on-premises network uses 10.0.0.0/8. The company wants to access an AWS service (e.g., S3) privately from the VPC without using public endpoints. Which solution avoids IP overlap and meets the requirement?
⚠ Common exam trap
Many exam-takers assume a private VIF can be used to reach AWS services privately, but they overlook the IP overlap between the VPC and on-premises networks, which breaks routing and makes Gateway VPC Endpoints the only viable solution.
Answer choices
Why each option matters
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 S3 (Gateway type) and use it from the VPC.
A Gateway VPC Endpoint for S3 allows private access to S3 from within the VPC without traversing the internet or requiring public IPs. It avoids IP overlap because the endpoint uses prefix lists and route table entries within the VPC's 10.0.0.0/16 range, and does not involve the on-premises 10.0.0.0/8 network. The Direct Connect private VIF is not used for S3 traffic, so the overlapping CIDR is irrelevant.
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 a NAT gateway in a public subnet and route S3 traffic through it.
Why it's wrong here
NAT gateway is for internet access, not private access to S3.
- ✓
Create a VPC endpoint for S3 (Gateway type) and use it from the VPC.
Why this is correct
VPC endpoint provides private access without overlapping IPs.
- ✗
Use a public virtual interface and access S3 via public endpoints.
Why it's wrong here
Public VIF does not keep traffic within AWS network.
- ✗
Add a route in the VPC route table pointing to the Direct Connect virtual interface for the S3 prefix list.
Why it's wrong here
Overlapping CIDRs will cause routing conflicts.
Visual reference
Quick reference
AWS S3 Storage Class Comparison
| Storage Class | Min Duration | Retrieval | Use Case |
|---|---|---|---|
| S3 Standard | None | Immediate | Frequently accessed data |
| S3 Standard-IA | 30 days | Immediate | Infrequent access, rapid retrieval |
| S3 One Zone-IA | 30 days | Immediate | Non-critical infrequent data |
| S3 Intelligent-Tiering | None | Immediate–hours | Unknown or changing access patterns |
| S3 Glacier Instant | 90 days | Milliseconds | Archive with instant retrieval |
| S3 Glacier Flexible | 90 days | Minutes–hours | Archive, flexible retrieval |
| S3 Glacier Deep Archive | 180 days | Hours | Long-term compliance archive |
Go deeper
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JA
Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
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.