ANS-C01 Internet Gateway Practice Question
A company is deploying a new VPC with public and private subnets. The VPC will host web servers in the public subnet and database servers in the private subnet. The web servers need to access the internet for updates, and the database servers need to receive traffic only from the web servers. Which THREE components are essential for this architecture?
⚠ Common exam trap
Candidates often mistakenly think a NAT gateway is required for the private subnet, but the database servers do not need internet access. Additionally, they may overlook Network ACLs as essential because security groups alone can allow traffic between web and database instances, but Network ACLs provide subnet-level control required by the architecture.
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
✓
Network ACL for subnets
An internet gateway (IGW) is essential to allow web servers in the public subnet to directly access the internet. Security groups are essential to control traffic between web and database servers, ensuring only web servers can access the database. Network ACLs are essential for subnet-level traffic control, such as allowing inbound traffic from the public subnet to the private subnet while denying other inbound traffic. A NAT gateway is not essential because the database servers do not require outbound internet access (only web servers need internet for updates). A VPC endpoint for S3 is not essential as there is no requirement to access S3.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
NAT gateway in the public subnet
Why it's wrong here
NAT gateway is not needed because web servers are in a public subnet and can use the Internet gateway for outbound internet access.
- ✓
Network ACL for subnets
Why this is correct
Network ACLs are essential for subnet-level security, controlling traffic between public and private subnets.
- ✓
Internet gateway
Why this is correct
Internet gateway is essential for web servers in the public subnet to access the internet.
- ✗
VPC endpoint for S3
Why it's wrong here
VPC endpoint for S3 is not essential for this architecture; internet updates can be obtained via the Internet gateway.
- ✓
Security groups for web and database servers
Why this is correct
Security groups are essential to restrict database servers to only accept traffic from web servers.
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 |
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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.