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.
Exhibit
Refer to the exhibit.
```
2024-03-15T10:00:00Z ERROR 500 GET /api/orders
2024-03-15T10:00:01Z ERROR 500 GET /api/orders
2024-03-15T10:00:02Z ERROR 500 GET /api/orders
... (repeated many times)
2024-03-15T10:05:00Z INFO 200 GET /api/health
2024-03-15T10:05:01Z ERROR 500 GET /api/orders
```
An application log excerpt shows repeated HTTP 500 errors for the /api/orders endpoint, with occasional successful health checks. The application runs on EC2 instances behind an ALB. What is the MOST likely cause of this pattern?
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.
Refer to the exhibit.
```
2024-03-15T10:00:00Z ERROR 500 GET /api/orders
2024-03-15T10:00:01Z ERROR 500 GET /api/orders
2024-03-15T10:00:02Z ERROR 500 GET /api/orders
... (repeated many times)
2024-03-15T10:05:00Z INFO 200 GET /api/health
2024-03-15T10:05:01Z ERROR 500 GET /api/orders
```
A
The backend service that the /api/orders endpoint depends on is unavailable or failing.
The endpoint consistently fails while health check succeeds, indicating a dependency issue.
B
The EC2 instances are running out of memory and the application is crashing.
Why wrong: Health check would likely fail if the application is crashing.
C
The ALB is misconfigured and routing requests to the wrong target group.
Why wrong: ALB misconfiguration would affect health checks too.
D
The EC2 instances are not passing health checks and are being deregistered from the target group.
Why wrong: Health checks return 200, so instances are healthy.
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
The backend service that the /api/orders endpoint depends on is unavailable or failing.
The pattern of repeated HTTP 500 errors for /api/orders with occasional successful health checks strongly indicates that the backend service dependency (e.g., a database, cache, or another microservice) is intermittently failing or unavailable. HTTP 500 errors are server-side errors, meaning the application code is running but cannot complete the request due to a downstream failure. Successful health checks confirm the EC2 instances themselves are healthy and in-service, ruling out instance-level or ALB misconfiguration issues.
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 backend service that the /api/orders endpoint depends on is unavailable or failing.
Why this is correct
The endpoint consistently fails while health check succeeds, indicating a dependency issue.
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 EC2 instances are running out of memory and the application is crashing.
Why it's wrong here
Health check would likely fail if the application is crashing.
✗
The ALB is misconfigured and routing requests to the wrong target group.
Why it's wrong here
ALB misconfiguration would affect health checks too.
✗
The EC2 instances are not passing health checks and are being deregistered from the target group.
Why it's wrong here
Health checks return 200, so instances are healthy.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates confuse HTTP 500 errors with instance-level failures (like OOM or health check failures), but the key differentiator is that successful health checks prove the instances are operational, shifting the root cause to a failing backend dependency rather than the compute layer.
Detailed technical explanation
How to think about this question
HTTP 500 errors originate from the application server (e.g., Tomcat, Nginx, or the application framework) when an unhandled exception occurs, often due to a failed downstream call (e.g., database connection timeout, Redis cluster down). The ALB's health check typically targets a lightweight endpoint (e.g., /health) that may not exercise the full dependency chain, so it can return 200 even when the /api/orders endpoint fails. In a microservices architecture, this pattern is a classic indicator of a 'partial outage' where the service is alive but its critical dependency is degraded.
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 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 exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
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 backend service that the /api/orders endpoint depends on is unavailable or failing. — The pattern of repeated HTTP 500 errors for /api/orders with occasional successful health checks strongly indicates that the backend service dependency (e.g., a database, cache, or another microservice) is intermittently failing or unavailable. HTTP 500 errors are server-side errors, meaning the application code is running but cannot complete the request due to a downstream failure. Successful health checks confirm the EC2 instances themselves are healthy and in-service, ruling out instance-level or ALB misconfiguration issues.
What should I do if I get this DOP-C02 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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Question Discussion
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