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.
An application running on Amazon ECS Fargate is experiencing intermittent HTTP 503 errors from the Application Load Balancer (ALB). The target group health checks are passing. Which configuration is MOST likely causing this 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 the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
The deregistration delay is set too short, causing connections to be closed before requests complete.
Option D is correct because a deregistration delay too short can cause the ALB to route traffic to a draining target, resulting in 503. Option A is wrong because health check interval being too short would cause flapping, not 503. Option B is wrong because slow start only affects new targets. Option C is wrong because circuit breaker doesn't cause 503s directly.
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.
✓
The deregistration delay is set too short, causing connections to be closed before requests complete.
Why this is correct
If delay is too short, in-flight requests may fail with 503 when a target is deregistered.
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.
✗
The ALB's slow start duration is too long, causing requests to be dropped.
Why it's wrong here
Slow start gradually increases traffic, it does not drop requests.
✗
The health check interval is set too low, causing targets to be marked unhealthy prematurely.
Why it's wrong here
Low interval would cause health check failures, not 503s if checks pass.
✗
The ALB's circuit breaker is tripping due to high error rates.
Why it's wrong here
Circuit breaker stops routing to unhealthy targets, but health checks pass.
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 cloud solutions architect for a retail company is evaluating services for a new workload. The correct answer here reflects best practice for the specific scenario described — not a general cloud recommendation. Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option. Cloud exam questions reward reading the constraint carefully: the same technology can be right or wrong depending on the use case.
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.
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: The deregistration delay is set too short, causing connections to be closed before requests complete. — Option D is correct because a deregistration delay too short can cause the ALB to route traffic to a draining target, resulting in 503. Option A is wrong because health check interval being too short would cause flapping, not 503. Option B is wrong because slow start only affects new targets. Option C is wrong because circuit breaker doesn't cause 503s directly.
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: "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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Question Discussion
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