ISC Infrastructure And System Security Practice Question
A cloud architect is defining a network security architecture for a multi-tier application. How should they protect the application tier from 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 app tier in a private subnet and restrict ingress to the ALB.
Place the application tier in a private subnet with no public IP, and allow traffic only from the Load Balancer (ELB) security group.
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 the app tier in a private subnet and restrict ingress to the ALB.
Why this is correct
This is the secure standard for multi-tier application architecture.
- ✗
Use a NACL to block all incoming traffic.
Why it's wrong here
If you block all traffic, the application cannot function.
- ✗
Deploy a WAF on each application instance.
Why it's wrong here
WAFs should be placed at the edge/load balancer layer, not on individual app instances.
- ✗
Attach a public IP to every instance in the app tier.
Why it's wrong here
This exposes the instances to the public internet directly.
Visual reference
About these practice questions
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JA
Written and reviewed by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
Last reviewed August 2026 · checked against the official (ISC)² exam blueprint
This ISC practice question is part of Courseiva's free (ISC)² 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 ISC exam.