The correct action is to add a listener rule on the ALB that checks the User-Agent header and returns a fixed response. This works because Application Load Balancer listener rules can evaluate HTTP headers like User-Agent as a condition, and the fixed-response action allows you to immediately reject unwanted traffic with a status code such as 403 Forbidden, all without modifying any application code. On the AWS Certified SysOps Administrator Associate SOA-C02 exam, this scenario tests your understanding of ALB rule-based traffic filtering versus relying on separate services like WAF or security groups, which cannot inspect header content. A common trap is choosing WAF, but remember that while WAF offers deeper inspection, the question explicitly requires a solution at the load balancer level using native ALB features. Memory tip: think "Rule + Header + Fixed Response" — the three ingredients for blocking bad user agents directly on the ALB.
SOA-C02 Networking and Content Delivery Practice Question
This SOA-C02 practice question tests your understanding of networking and content delivery. Read the scenario carefully and evaluate each option against the stated constraints before committing to an answer. 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 is using an Application Load Balancer (ALB) to distribute traffic to a fleet of EC2 instances. The security team reports that the ALB is receiving a high number of requests with suspicious User-Agent strings. The SysOps team needs to block these requests at the load balancer level without changing the application code. Which action should be taken?
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Add a listener rule on the ALB that checks the User-Agent header and returns a fixed response.
Option C is correct because ALB supports rules that evaluate conditions like User-Agent header and perform actions such as fixed-response to block requests. Option A is wrong because WAF is a separate service, not directly on ALB rules. Option B is wrong because modifying target group health checks does not block requests. Option D is wrong because security group rules do not inspect HTTP headers.
Key principle: ACLs process entries top to bottom and stop at the first match. Entry order and interface direction matter as much as the permit or deny statement.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
✗
Modify the security group of the ALB to deny traffic from User-Agent strings.
Why it's wrong here
Security groups do not inspect application-layer headers like User-Agent.
✗
Update the target group health check to filter out suspicious User-Agent strings.
Why it's wrong here
Health checks are for instance health, not for filtering incoming requests.
✓
Add a listener rule on the ALB that checks the User-Agent header and returns a fixed response.
Why this is correct
ALB listener rules can inspect headers and return a 403 or fixed response.
Related concept
Standard ACLs match source addresses.
✗
Deploy AWS WAF and associate it with the ALB.
Why it's wrong here
WAF can work with ALB but is not the only option; ALB rules can also block requests without WAF.
Common exam traps
Common exam trap: ACLs stop at the first match
ACLs are processed top to bottom. The first matching entry wins, and an implicit deny usually exists at the end.
Detailed technical explanation
How to think about this question
ACL questions test precision: source, destination, protocol, port and direction. A generally correct ACL can still fail if it is applied on the wrong interface or in the wrong direction.
KKey Concepts to Remember
Standard ACLs match source addresses.
Extended ACLs can match source, destination, protocol and ports.
The first matching ACL entry is used.
There is usually an implicit deny at the end.
TExam Day Tips
→Check inbound versus outbound direction.
→Read the ACL from top to bottom.
→Look for a broader permit or deny above the intended line.
Key takeaway
ACLs process entries top to bottom and stop at the first match. Entry order and interface direction matter as much as the permit or deny statement.
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.
Review ACL processing order, placement rules (standard near destination, extended near source), and inbound vs outbound direction. Study wildcard masks and implicit deny. Then practise related SOA-C02 ACL questions on filtering logic and placement.
Networking and Content Delivery — This question tests Networking and Content Delivery — Standard ACLs match source addresses..
What is the correct answer to this question?
The correct answer is: Add a listener rule on the ALB that checks the User-Agent header and returns a fixed response. — Option C is correct because ALB supports rules that evaluate conditions like User-Agent header and perform actions such as fixed-response to block requests. Option A is wrong because WAF is a separate service, not directly on ALB rules. Option B is wrong because modifying target group health checks does not block requests. Option D is wrong because security group rules do not inspect HTTP headers.
What should I do if I get this SOA-C02 question wrong?
Review ACL processing order, placement rules (standard near destination, extended near source), and inbound vs outbound direction. Study wildcard masks and implicit deny. Then practise related SOA-C02 ACL questions on filtering logic and placement.
What is the key concept behind this question?
Standard ACLs match source addresses.
About these practice questions
Courseiva creates original exam-style practice questions with explanations and wrong-answer analysis. It does not publish real exam questions, exam dumps, or protected exam content. Learn why practice questions differ from exam dumps →
Share a tip, memory trick, or ask about the reasoning behind this question. Do not post real exam questions, leaked content, braindumps, or copyrighted exam material. Comments are moderated and may be removed without notice.
This SOA-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 SOA-C02 exam.
Question Discussion
Share a tip, memory trick, or ask about the reasoning behind this question. Do not post real exam questions, leaked content, braindumps, or copyrighted exam material. Comments are moderated and may be removed without notice.
Sign in to join the discussion.