ANS-C01 Network Implementation Practice Question
A company is deploying a multi-tier web application in a VPC. The web tier must be accessible from the internet, while the application tier must only be accessible from the web tier. The database tier must only be accessible from the application tier. Which design best meets these requirements?
⚠ Common exam trap
The ANS-C01 exam often tests the misconception that security groups alone can secure tiers placed in public subnets, but the trap here is that a public subnet with an Internet Gateway route inherently allows inbound internet traffic unless explicitly blocked by a network ACL, so the application and database tiers must be placed in private subnets to prevent direct internet access.
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
✓
Place the web tier in public subnets with an internet gateway, and the application and database tiers in private subnets. Use security groups to allow traffic from the web tier to the application tier, and from the application tier to the database tier.
It places the web tier in a public subnet with an Internet Gateway (IGW) for direct internet access, while the application and database tiers reside in private subnets with no direct internet path. Security groups act as stateful virtual firewalls at the instance level, allowing you to specify inbound rules that permit traffic only from the web tier security group to the application tier, and from the application tier security group to the database tier. This layered approach enforces the principle of least privilege and meets the access requirements without exposing the internal tiers to 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.
- ✗
Place all tiers in public subnets and use security groups to control traffic between tiers.
Why it's wrong here
Incorrect: public subnets expose app and DB to internet, not secure.
- ✓
Place the web tier in public subnets with an internet gateway, and the application and database tiers in private subnets. Use security groups to allow traffic from the web tier to the application tier, and from the application tier to the database tier.
Why this is correct
Correct design: public subnet with IGW for web, private subnets for app and DB, security groups restrict traffic.
- ✗
Place all tiers in the same subnet and use network ACLs to restrict traffic between tiers.
Why it's wrong here
Incorrect: single subnet cannot isolate tiers; subnets are in the same VPC but traffic flows through route tables and security groups.
- ✗
Place the web tier in a private subnet and use a NAT gateway for outbound internet access. Place the application and database tiers in public subnets.
Why it's wrong here
Incorrect: web tier needs inbound internet access, private subnet cannot receive internet traffic without a load balancer in a public subnet.
Visual reference
Go deeper
Related to this question
About these practice questions
This ANS-C01 question is part of Courseiva's 1,621-question bank — original exam-style content with full explanations and wrong-answer analysis, never real exam questions or exam dumps. Learn why practice questions differ from exam dumps →
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.