ANS-C01 Network Security, Compliance and Governance Practice Question
A security engineer is designing a VPC with public and private subnets. The company requires that instances in the private subnet can initiate outbound connections to the internet but cannot receive inbound connections from the internet. Which TWO components are necessary? (Choose 2)
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
✓
NAT Gateway in the public subnet
To allow instances in a private subnet to initiate outbound internet connections while preventing inbound connections, a NAT Gateway placed in a public subnet is required. The NAT Gateway translates private IPs to its own public IP. Additionally, the private subnet's route table must have a default route (0.0.0.0/0) pointing to the NAT Gateway to direct outbound traffic. Option A (VPC Gateway Endpoint for S3) is for private access to S3, not general internet. Option B (security group allowing inbound from 0.0.0.0/0) would allow inbound connections, violating the requirement. Option D (Internet Gateway attached to private subnet) is incorrect because an Internet Gateway is attached to the VPC, not a subnet, and would allow inbound traffic if used in a route table.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
VPC Gateway Endpoint for S3
Why it's wrong here
Gateway Endpoint is for AWS services, not general internet.
- ✗
Security group allowing inbound traffic from 0.0.0.0/0
Why it's wrong here
Inbound from internet is not allowed per requirement.
- ✓
NAT Gateway in the public subnet
Why this is correct
NAT Gateway enables outbound internet from private subnets.
- ✗
Internet Gateway attached to the private subnet
Why it's wrong here
Internet Gateway is attached to VPC, not subnet.
- ✓
Route in the private subnet route table pointing to the NAT Gateway
Why this is correct
Route directs outbound traffic to NAT Gateway.
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.