CCSP Cloud Platform and Infrastructure Security Practice Question
A company is deploying a multi-tier application on AWS. They need to protect the application layer from common web attacks and also restrict traffic between tiers. Which TWO network security controls should they use?
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
✓
AWS WAF integrated with Application Load Balancer
Option B (AWS WAF integrated with Application Load Balancer) is correct because AWS WAF inspects HTTP/HTTPS requests at Layer 7 and can block common web exploits such as SQL injection and cross-site scripting using managed rule groups attached to an ALB, directly satisfying the requirement to protect the application layer. Option C (Security groups between application tiers) is correct because security groups are stateful, instance-level virtual firewalls whose inbound rules can reference other security groups, allowing precise tier-to-tier traffic restriction (for example, permitting only the app tier's SG to reach the database tier on port 3306). Option A is not appropriate here because PrivateLink provides private connectivity to services and endpoints, not application-layer attack filtering or inter-tier traffic control. Option D is wrong because VPC peering only connects networks for routing and does not filter or restrict traffic between application tiers. Option E is less suitable because network ACLs are stateless, subnet-level filters that cannot reference security groups or enforce granular per-tier application rules as cleanly as security groups.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
PrivateLink for database access
Why it's wrong here
PrivateLink exposes a service privately to other VPCs or accounts; it cannot inspect HTTP traffic for web attacks, nor filter tier-to-tier flows. It is tempting because it secures database access by removing internet exposure, which would be correct if the requirement were private connectivity to a database rather than application-layer protection.
- ✓
AWS WAF integrated with Application Load Balancer
Why this is correct
AWS WAF attached to an Application Load Balancer inspects HTTP/HTTPS requests at layer 7, blocking SQL injection, cross-site scripting and similar OWASP threats. This satisfies the requirement to protect the application layer from common web attacks.
- ✓
Security groups between application tiers
Why this is correct
Security groups are stateful, instance-level virtual firewalls whose rules reference other security groups as sources. Attaching distinct groups per tier permits only the required ports between tiers, satisfying the requirement to restrict east-west traffic between application tiers.
- ✗
VPC peering with all VPCs
Why it's wrong here
VPC peering merely connects networks, permitting traffic by default once routes and security groups allow it; it provides no application-layer inspection and no tier segmentation. It is tempting because peering is the standard way to join VPCs, and would be correct where two VPCs must exchange traffic privately without a transit gateway.
- ✗
Network ACLs for each subnet
Why it's wrong here
Network ACLs are stateless subnet-level filters operating on IP, port and protocol; they cannot detect SQL injection or cross-site scripting at the application layer. They are tempting because they do restrict traffic between tiers, and would be correct where the requirement is coarse subnet-level allow/deny rules rather than web attack inspection.
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JA
Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
This CCSP practice question is part of Courseiva's free ISC2 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 CCSP exam.