ANS-C01 Network Security, Compliance and Governance Practice Question
A company wants to block incoming traffic from specific IP addresses at the edge of the AWS network before it reaches the application load balancer. Which AWS service should be used?
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 web ACL associated with the ALB
AWS WAF can be associated with an Application Load Balancer to filter incoming traffic based on IP addresses at the edge (before reaching the ALB). Option B is wrong because Network ACLs operate at the subnet level and do not inspect HTTP traffic or block at the edge. Option C is wrong because Security Groups are stateful firewalls that operate at the instance or ENI level, not at the edge, and they cannot block traffic before the ALB. Option D is wrong because CloudFront is a CDN that can be used with WAF, but the question specifically asks for blocking at the edge before the ALB, and CloudFront alone does not provide IP filtering for an ALB without WAF.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✓
AWS WAF web ACL associated with the ALB
Why this is correct
AWS WAF can block IP addresses using IP set match conditions at the ALB level.
- ✗
Network ACLs on the VPC subnet containing the ALB
Why it's wrong here
Network ACLs are stateless and operate at Layer 3/4; they cannot inspect HTTP traffic or block based on IP sets easily.
- ✗
Security Groups attached to the ALB
Why it's wrong here
Security Groups are attached to ENIs, not to ALBs; they also do not support IP-based deny rules.
- ✗
Amazon CloudFront with origin access identity
Why it's wrong here
CloudFront is a CDN; while it can be used with WAF, it does not block traffic at the ALB edge directly.
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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.