- A
Enable and analyze the ALB access logs stored in S3, filtering for 503 errors and correlating with target response times.
Access logs provide detailed per-request data including timestamp, target status, and response time, enabling correlation of errors with slow targets.
- B
Increase the desired capacity of the Auto Scaling group to handle more requests.
Why wrong: This may temporarily reduce errors but does not identify the root cause; could be cost-ineffective.
- C
Disable connection draining on the target group to prevent slow-draining instances from causing errors.
Why wrong: Connection draining helps gracefully terminate connections; disabling it may cause more errors during instance replacement.
- D
Review AWS CloudTrail logs for any recent configuration changes to the ALB.
Why wrong: CloudTrail logs API calls, not HTTP-level errors; 503 errors are not captured there.
Quick Answer
The correct first step is to enable and analyze the ALB access logs stored in S3, filtering for 503 errors and correlating them with target response times. This approach directly addresses the intermittent 503 errors by allowing you to pinpoint whether the errors align with spikes in latency from specific targets, revealing issues like resource exhaustion or application bottlenecks that CloudWatch metrics alone cannot isolate. On the AWS Certified DevOps Engineer Professional DOP-C02 exam, this scenario tests your ability to choose the most granular diagnostic tool before making configuration changes—a common trap is jumping to scaling actions or misreading CloudTrail logs, which record API calls, not HTTP traffic. Remember, access logs are your forensic microscope for ALB errors; CloudWatch shows the fever, but access logs find the infection. A useful memory tip: "Logs before knobs"—always inspect the data before turning any dials.
DOP-C02 Incident and Event Response Practice Question
This DOP-C02 practice question tests your understanding of incident and event response. 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 runs a critical web application on EC2 instances behind an Application Load Balancer (ALB) with Auto Scaling. Users report intermittent 503 errors. CloudWatch metrics show that the ALB's 'RequestCount' is normal, but 'HTTPCode_ELB_5XX_Count' spikes. The 'TargetResponseTime' metric shows occasional high latency. Which troubleshooting step should the DevOps engineer take FIRST?
Clue words in this question
Noticing these words before you look at the options changes how you read each choice.
Clue:
"first"Why it matters: Order matters here. You are being tested on which action comes before the others — not which action is generally useful.
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
Enable and analyze the ALB access logs stored in S3, filtering for 503 errors and correlating with target response times.
Option C is correct because checking the ALB's access logs for 503 errors with their timestamps can reveal whether the errors coincide with high latency targets. Option A is wrong because increasing capacity does not address the root cause. Option B is wrong because CloudTrail logs API calls, not HTTP errors. Option D is wrong because disabling connection draining could worsen the issue.
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.
- ✓
Enable and analyze the ALB access logs stored in S3, filtering for 503 errors and correlating with target response times.
Why this is correct
Access logs provide detailed per-request data including timestamp, target status, and response time, enabling correlation of errors with slow targets.
Clue confirmation
The clue word "first" in the question point toward this answer.
Related concept
Read the scenario before looking for a memorised answer.
- ✗
Increase the desired capacity of the Auto Scaling group to handle more requests.
Why it's wrong here
This may temporarily reduce errors but does not identify the root cause; could be cost-ineffective.
- ✗
Disable connection draining on the target group to prevent slow-draining instances from causing errors.
Why it's wrong here
Connection draining helps gracefully terminate connections; disabling it may cause more errors during instance replacement.
- ✗
Review AWS CloudTrail logs for any recent configuration changes to the ALB.
Why it's wrong here
CloudTrail logs API calls, not HTTP-level errors; 503 errors are not captured there.
Common exam traps
Common exam trap: answer the scenario, not the keyword
Many certification questions include familiar terms but test a specific constraint. Read the exact wording before choosing an answer that is generally true but wrong for this case.
Detailed technical explanation
How to think about this question
This question should be treated as a scenario, not a definition check. Identify the problem, the constraint and the best action. Then compare each option against those facts.
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.
- Use explanations to understand the rule behind the answer.
TExam Day Tips
- Underline the problem statement mentally.
- 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 media company stores terabytes of video archives that are accessed once a year for audit purposes. Moving these objects to a cold storage tier (Azure Archive, S3 Glacier, or Google Nearline) costs a fraction of hot storage. Questions like this test whether you understand storage tiers, access frequency tradeoffs, and retrieval latency requirements.
What to study next
Got this wrong? Here's your next step.
Identify which DOP-C02 exam domain this question belongs to, then review the specific concept being tested. Practise related questions in that domain and focus on understanding why each wrong answer is tempting — not just why the correct answer is right.
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Incident and Event Response — study guide chapter
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FAQ
Questions learners often ask
What does this DOP-C02 question test?
Incident and Event Response — This question tests Incident and Event Response — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: Enable and analyze the ALB access logs stored in S3, filtering for 503 errors and correlating with target response times. — Option C is correct because checking the ALB's access logs for 503 errors with their timestamps can reveal whether the errors coincide with high latency targets. Option A is wrong because increasing capacity does not address the root cause. Option B is wrong because CloudTrail logs API calls, not HTTP errors. Option D is wrong because disabling connection draining could worsen the issue.
What should I do if I get this DOP-C02 question wrong?
Identify which DOP-C02 exam domain this question belongs to, then review the specific concept being tested. Practise related questions in that domain and focus on understanding why each wrong answer is tempting — not just why the correct answer is right.
Are there clue words in this question I should notice?
Yes — watch for: "first". Order matters here. You are being tested on which action comes before the others — not which action is generally useful.
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 →
Same concept, more angles
1 more ways this is tested on DOP-C02
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. A company's application running on EC2 instances behind an Application Load Balancer (ALB) is returning intermittent 504 errors. The instances are in an Auto Scaling group with a health check grace period of 300 seconds. What should the DevOps engineer check first to troubleshoot the issue?
medium- A.Review the Auto Scaling group scaling policies.
- B.Verify the target group health checks are passing.
- C.Check security group rules for the ALB.
- ✓ D.Check ALB access logs for target response times.
Why D: Option A is correct because 504 errors indicate the load balancer is not receiving a response from the target within the idle timeout period. Checking the ALB access logs for target response times can confirm if the backend is slow. Option B is wrong because if the ELB is not healthy, the instances would be replaced, but the issue is intermittent. Option C is wrong because scaling policies affect capacity, not response times. Option D is wrong because security group rules would cause connection timeouts, not 504s.
Last reviewed: Jun 20, 2026
This DOP-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 DOP-C02 exam.
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