ANS-C01 Network Implementation Practice Question
A company is running a two-tier application with a web tier and a database tier. The web tier must be accessible from the internet, but the database tier should only be accessible from the web tier. Which architecture should they use?
⚠ Common exam trap
The ANS-C01 exam often tests the misconception that security groups alone can secure a database in a public subnet, but the trap here is that a public subnet inherently provides a route to the internet via an internet gateway, making the database reachable from the internet even with restrictive security groups.
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
✓
Web tier in public subnet, database tier in private subnet with a security group allowing only web tier.
The correct architecture places the web tier in a public subnet with an internet gateway for inbound traffic, and the database tier in a private subnet with a security group that only allows inbound traffic from the web tier's security group. This ensures the database is not directly reachable from the internet, adhering to the principle of least privilege and defense in depth. The security group acts as a stateful virtual firewall, allowing you to reference the web tier's security group as the source, which automatically adapts to any changes in the web tier's IP addresses.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✓
Web tier in public subnet, database tier in private subnet with a security group allowing only web tier.
Why this is correct
This architecture provides internet access to the web tier and isolates the database.
- ✗
Both tiers in public subnets with security groups restricting database access.
Why it's wrong here
Placing the database in a public subnet exposes it unnecessarily.
- ✗
Both tiers in private subnets with a NAT Gateway for internet access.
Why it's wrong here
A NAT Gateway would not allow inbound internet traffic to the web tier.
- ✗
Web tier in private subnet, database tier in public subnet with a security group.
Why it's wrong here
This exposes the database to the internet.
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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.