The correct answer is to increase the idle timeout setting on the Application Load Balancer. This resolves the ALB idle timeout causing 503 errors because the default idle timeout is 60 seconds for ALB, but the application’s target response time exceeds 30 seconds, meaning the backend is still processing when the ALB prematurely closes the connection. On the AWS Certified SysOps Administrator Associate SOA-C02 exam, this scenario tests your understanding of how ALB connection settings interact with backend latency—a common trap is confusing idle timeout with the deregistration delay or health check intervals. The key insight is that the 503 error is not a backend failure but a timeout at the load balancer level, so increasing the idle timeout to a value higher than the application’s maximum expected response time (e.g., 120 seconds) allows the request to complete normally. Memory tip: think “idle = wait time for data,” so if your app is slow, raise the idle to let it finish.
SOA-C02 Monitoring, Logging, and Remediation Practice Question
This SOA-C02 practice question tests your understanding of monitoring, logging, and remediation. Examine the command output carefully: the correct answer depends on what the output actually shows, not on general recall alone. 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 has an application running on Amazon EC2 instances behind an Application Load Balancer (ALB). The application logs show intermittent 503 errors. The ALB access logs show that the errors occur when the target response time exceeds 30 seconds. Which configuration change should the SysOps administrator make to reduce the number of 503 errors without affecting the application's behavior?
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Increase the idle timeout setting on the ALB
The 503 errors occur when the target response time exceeds 30 seconds, which matches the default idle timeout of the Application Load Balancer. By increasing the idle timeout setting on the ALB to a value higher than the application's maximum expected response time (e.g., 60 or 120 seconds), the ALB will wait longer before closing the connection, preventing premature 503 errors while the backend is still processing the request.
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.
✗
Increase the deregistration delay on the target group
Why it's wrong here
Deregistration delay controls how long the ALB waits before terminating a target, not request timeouts.
✓
Increase the idle timeout setting on the ALB
Why this is correct
ALB idle timeout is the maximum time the load balancer waits for a response. Increasing it allows longer-running requests to complete.
Related concept
Read the scenario before looking for a memorised answer.
✗
Enable cross-zone load balancing on the ALB
Why it's wrong here
Cross-zone load balancing distributes traffic evenly across targets but does not affect request timeout.
✗
Decrease the health check interval on the target group
Why it's wrong here
Decreasing health check interval may cause more frequent health checks, potentially marking targets unhealthy more often.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates often confuse the ALB idle timeout with the target group deregistration delay or health check settings, mistakenly thinking that adjusting health checks or deregistration will fix timeout-related 503 errors, when the root cause is the ALB's connection timeout parameter.
Detailed technical explanation
How to think about this question
The ALB idle timeout is defined at the listener level and defaults to 60 seconds for HTTP/HTTPS, but the 30-second threshold mentioned in the question suggests a custom or lower setting (possibly 30 seconds) or the application's response time is exceeding the default. Under the hood, the ALB closes the connection if no data is sent or received within the idle timeout period, sending a 503 to the client; increasing this timeout allows long-running requests (e.g., database queries or file processing) to complete without interruption. In real-world scenarios, this is common for applications that generate reports or process large uploads where the backend takes more than 30 seconds to respond.
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.
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
Monitoring, Logging, and Remediation — This question tests Monitoring, Logging, and Remediation — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: Increase the idle timeout setting on the ALB — The 503 errors occur when the target response time exceeds 30 seconds, which matches the default idle timeout of the Application Load Balancer. By increasing the idle timeout setting on the ALB to a value higher than the application's maximum expected response time (e.g., 60 or 120 seconds), the ALB will wait longer before closing the connection, preventing premature 503 errors while the backend is still processing the request.
What should I do if I get this SOA-C02 question wrong?
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
What is the key concept behind this question?
Read the scenario before looking for a memorised answer.
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 →
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. An application running on Amazon EC2 instances behind an Application Load Balancer (ALB) is experiencing intermittent 5xx errors. CloudWatch metrics show that the ALB's 'HTTPCode_ELB_5XX_Count' is elevated. What is the MOST likely cause?
medium
A.The target instances are returning HTTP 503 errors.
B.The target instances have high latency but are still responding.
✓ C.The load balancer is timing out waiting for a response from the target.
D.Client requests are malformed and being rejected by the load balancer.
Why C: When the ALB's 'HTTPCode_ELB_5XX_Count' is elevated, it indicates that the load balancer itself is generating the 5xx error, not the target. The most common cause is that the load balancer is timing out while waiting for a response from the target instances, which occurs when the target takes longer than the configured idle timeout (default 60 seconds) to respond. This results in the ALB returning a 504 Gateway Timeout error, which is counted in the ELB 5xx metric.
Last reviewed: Jun 24, 2026
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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.
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