This SCS-C02 practice question tests your understanding of infrastructure security. The scenario asks you to isolate a root cause — eliminate options that address a different problem before choosing. After answering, compare your reasoning against the explanation and wrong-answer breakdown below. Once you have made your selection, read the full explanation to reinforce the concept and understand why each distractor is designed to mislead on exam day.
A company wants to block traffic from a specific IP address range from accessing an Application Load Balancer (ALB). Which AWS feature should be used?
Network ACL
Why wrong: Operates at subnet level, not on ALB.
Security Group for the ALB
Why wrong: Security groups are not supported for ALBs?
Route53
Why wrong: DNS service, not a firewall.
AWS WAF
Web application firewall that can filter by IP.
Answer choices
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
AWS WAF
Option B is correct because AWS WAF can be associated with an ALB to filter traffic based on IP addresses. Option A is wrong because security groups cannot be associated with ALBs in the same way as EC2. Option C is wrong because Network ACLs operate at the subnet level, not directly on the ALB. Option D is wrong because Route53 does not filter traffic.
Key principle: Count usable hosts — not total addresses — and remember that the network and broadcast addresses are not available to hosts in standard IPv4 subnets.
Answer analysis
For each option: why learners choose it and why it is or isn't the right answer here.
Network ACL
Why it's wrong here
Operates at subnet level, not on ALB.
Security Group for the ALB
Why it's wrong here
Security groups are not supported for ALBs?
Route53
AWS WAF
Common exam traps
Subnetting questions often tempt you into counting all addresses. In normal IPv4 subnets, the network and broadcast addresses are not usable host addresses.
Detailed technical explanation
Subnetting questions test whether you can identify the network, broadcast address, usable range, mask and correct subnet. Slow down enough to calculate the block size correctly.
Key takeaway
Count usable hosts — not total addresses — and remember that the network and broadcast addresses are not available to hosts in standard IPv4 subnets.
Real-world example
A company's IT admin needs to give a contractor read-only access to production logs without sharing account credentials. Using role-based access control (RBAC) and temporary scoped permissions — not a permanent shared password — is the correct pattern. Questions like this test whether you can apply least-privilege access across cloud identity services.
What to study next
Review block sizes, usable host formulas (2^n − 2), and how to find network and broadcast addresses for /24 through /30. Then practise related SCS-C02 subnetting questions on CIDR, address ranges, and subnet selection.
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FAQ
Infrastructure Security — This question tests Infrastructure Security — CIDR notation defines the prefix length..
The correct answer is: AWS WAF — Option B is correct because AWS WAF can be associated with an ALB to filter traffic based on IP addresses. Option A is wrong because security groups cannot be associated with ALBs in the same way as EC2. Option C is wrong because Network ACLs operate at the subnet level, not directly on the ALB. Option D is wrong because Route53 does not filter traffic.
Review block sizes, usable host formulas (2^n − 2), and how to find network and broadcast addresses for /24 through /30. Then practise related SCS-C02 subnetting questions on CIDR, address ranges, and subnet selection.
CIDR notation defines the prefix length.
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Last reviewed: Jun 20, 2026
This SCS-C02 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 SCS-C02 exam.
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