- A
Associate the Web ACL with the Application Load Balancer resource ARN so WAF evaluates requests sent to that ALB.
For an ALB, the Web ACL must be associated with the load balancer resource itself. If it is not attached to the ALB, WAF will not inspect those requests.
- B
Add a security group rule that drops inbound traffic from the attacker IP range at the instances' ENIs.
Why wrong: Security groups can block traffic, but this does not fix the fact that WAF is not evaluating the requests.
- C
Create a target group stickiness policy so WAF can count requests consistently per client IP.
Why wrong: Stickiness affects load balancing behavior, not whether WAF evaluates requests.
- D
Enable AWS Shield Advanced but keep the Web ACL unattached because Shield automatically applies rate limiting.
Why wrong: Shield protects against certain DDoS conditions, but it does not replace WAF association or WAF rate-based rules.
Quick Answer
The answer is to associate the Web ACL with the Application Load Balancer resource ARN, because AWS WAF does not automatically evaluate traffic for any resource—a Web ACL must be explicitly attached to a specific resource like an ALB, CloudFront distribution, or API Gateway for it to inspect incoming requests. In this scenario, the Web ACL was deployed but never linked to the ALB, so the rate-based rule was effectively inactive, allowing attackers to reach the backend despite the rule being configured. On the SAA-C03 exam, this tests your understanding that WAF is a separate service from the ALB itself, and a common trap is assuming that creating a Web ACL is enough to protect a resource without performing the association step. A helpful memory tip is to think of the Web ACL as a security guard who needs a specific assignment to a building—without that assignment, the guard has no authority to check anyone entering.
SAA-C03 Design Secure Architectures Practice Question
This SAA-C03 practice question tests your understanding of design secure architectures. 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.
You deploy a Web ACL with an AWS WAF rate-based rule intended to limit abusive traffic to your API. After the deployment, attackers still reach the backend service. ALB access logs show requests arrive at the ALB, but WAF logs indicate the Web ACL is not evaluating those requests.
Which change most likely fixes the issue?
Clue words in this question
Noticing these words before you look at the options changes how you read each choice.
Clue:
"most likely"Why it matters: Probability qualifier — the question wants the most probable cause or outcome, not a guaranteed one. Eliminate low-probability options.
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
Associate the Web ACL with the Application Load Balancer resource ARN so WAF evaluates requests sent to that ALB.
A Web ACL must be explicitly associated with a resource (such as an ALB) for AWS WAF to evaluate incoming requests. In this scenario, the Web ACL was deployed but not associated with the ALB resource ARN, so WAF never inspected the traffic. Associating the Web ACL with the ALB ensures that all requests to the ALB are evaluated by the rate-based rule before reaching the backend.
Key principle: Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✓
Associate the Web ACL with the Application Load Balancer resource ARN so WAF evaluates requests sent to that ALB.
Why this is correct
For an ALB, the Web ACL must be associated with the load balancer resource itself. If it is not attached to the ALB, WAF will not inspect those requests.
Clue confirmation
The clue word "most likely" in the question point toward this answer.
Related concept
Read the scenario before looking for a memorised answer.
- ✗
Add a security group rule that drops inbound traffic from the attacker IP range at the instances' ENIs.
Why it's wrong here
Security groups can block traffic, but this does not fix the fact that WAF is not evaluating the requests.
- ✗
Create a target group stickiness policy so WAF can count requests consistently per client IP.
Why it's wrong here
Stickiness affects load balancing behavior, not whether WAF evaluates requests.
- ✗
Enable AWS Shield Advanced but keep the Web ACL unattached because Shield automatically applies rate limiting.
Why it's wrong here
Shield protects against certain DDoS conditions, but it does not replace WAF association or WAF rate-based rules.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates assume deploying a Web ACL automatically applies it to all resources in the account, when in fact it must be explicitly associated with each resource ARN to take effect.
Detailed technical explanation
How to think about this question
AWS WAF Web ACLs are regional or global resources that must be associated with a supported resource (ALB, API Gateway, CloudFront) via the resource ARN. Without this association, the Web ACL exists but is inactive—no traffic flows through it. Rate-based rules use a sliding window of requests from a single IP; if the Web ACL is not associated, the rule never sees traffic, so the rate limit is never enforced.
KKey Concepts to Remember
- Read the scenario before looking for a memorised answer.
- Find the constraint that changes the correct option.
- Eliminate answers that are true in general but not in this case.
TExam Day Tips
- Watch for words such as best, first, most likely and least administrative effort.
- Review why wrong options are wrong, not only why the correct option is correct.
Key takeaway
Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Real-world example
How this comes up in practice
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
Got this wrong? Here's your next step.
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FAQ
Questions learners often ask
What does this SAA-C03 question test?
Design Secure Architectures — This question tests Design Secure Architectures — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: Associate the Web ACL with the Application Load Balancer resource ARN so WAF evaluates requests sent to that ALB. — A Web ACL must be explicitly associated with a resource (such as an ALB) for AWS WAF to evaluate incoming requests. In this scenario, the Web ACL was deployed but not associated with the ALB resource ARN, so WAF never inspected the traffic. Associating the Web ACL with the ALB ensures that all requests to the ALB are evaluated by the rate-based rule before reaching the backend.
What should I do if I get this SAA-C03 question wrong?
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
Are there clue words in this question I should notice?
Yes — watch for: "most likely". Probability qualifier — the question wants the most probable cause or outcome, not a guaranteed one. Eliminate low-probability options.
What is the key concept behind this question?
Read the scenario before looking for a memorised answer.
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Same concept, more angles
1 more ways this is tested on SAA-C03
These questions test the same concept from different angles. Work through them to make sure you can recognise it however the exam phrases it.
Variation 1. You deploy a Web ACL with an AWS WAF rate-based rule intended to limit abusive traffic to your API. After the deployment, attackers still reach the backend service. ALB access logs show requests arrive at the ALB, but WAF logs indicate the Web ACL is not evaluating those requests. Which change most likely fixes the issue?
medium- ✓ A.Associate the Web ACL with the Application Load Balancer resource ARN so WAF evaluates requests sent to that ALB.
- B.Add a security group rule that drops inbound traffic from the attacker IP range at the instances' ENIs.
- C.Create a target group stickiness policy so WAF can count requests consistently per client IP.
- D.Enable AWS Shield Advanced but keep the Web ACL unattached because Shield automatically applies rate limiting.
Why A: The Web ACL must be explicitly associated with the ALB resource ARN for AWS WAF to evaluate incoming requests. Without this association, WAF does not inspect traffic, allowing attackers to bypass the rate-based rule and reach the backend service. Associating the Web ACL with the ALB ensures that all requests to the ALB are evaluated by the WAF rules before being forwarded to the target group.
Last reviewed: Jun 11, 2026
This SAA-C03 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 SAA-C03 exam.
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