ANS-C01 Network Design Practice Question
A company is designing a network for a multi-tier application that must meet compliance requirements. The architecture includes a VPC with public, private, and database subnets. Which TWO actions should be taken to ensure the database subnets are not directly accessible from the internet? (Select TWO.)
⚠ Common exam trap
The ANS-C01 exam often tests the misconception that a security group deny rule can block inbound traffic from 0.0.0.0/0, but security groups only support allow rules and are stateful, so the correct approach is to use a network ACL deny rule or place the subnets in a private subnet without an Internet Gateway route.
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
✓
Configure a network ACL on the database subnets to deny inbound traffic from 0.0.0.0/0.
A network ACL (NACL) is a stateless firewall that operates at the subnet level. By configuring a NACL rule to deny inbound traffic from 0.0.0.0/0, you explicitly block all internet-originated traffic from reaching the database subnets, regardless of any security group rules. Option E is correct because placing the database subnets in private subnets means they have no direct route to an Internet Gateway, making them inherently inaccessible from the internet.
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 database subnets.
Why it's wrong here
Wrong: This would expose them to the internet.
- ✗
Create a NAT Gateway in the database subnets.
Why it's wrong here
Wrong: NAT Gateway is not needed for database isolation.
- ✗
Associate a security group that denies inbound traffic from 0.0.0.0/0.
Why it's wrong here
Wrong: Security groups only support allow rules, not deny.
- ✓
Configure a network ACL on the database subnets to deny inbound traffic from 0.0.0.0/0.
Why this is correct
Correct: Network ACLs can deny inbound traffic.
- ✓
Place the database subnets in private subnets.
Why this is correct
Correct: Private subnets have no direct route to IGW.
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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.