The answer is that the Lambda execution role lacks permissions to create log streams and put log events. This is the most likely cause because when a Lambda function is invoked but cannot write logs, CloudWatch shows the log group exists with zero storedBytes, indicating the function never successfully delivered log data. The execution role must include specific IAM actions like logs:CreateLogStream and logs:PutLogEvents on the log group resource; without these, the function silently fails to log. On the AWS Certified DevOps Engineer Professional DOP-C02 exam, this scenario tests your understanding of IAM permissions as a root cause for missing CloudWatch logs—a common trap is assuming log group retention or throttling is at fault. Remember, a log group with zero bytes means the role is the blocker, not the group itself. Memory tip: “Zero bytes, check the rights” — if storedBytes is 0, the role likely lacks write permissions.
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.
Network Topology
A Lambda function 'my-function' is invoked multiple times, but no logs appear in CloudWatch. The DevOps engineer runs the above CLI command and sees that the log group exists but 'storedBytes' is 0. What is the MOST likely cause?
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 Lambda execution role lacks permissions to create log streams and put log events.
Option D is correct because the Lambda function's execution role must have permissions to create log streams and put log events. Without these permissions, the function cannot write logs. Option A is wrong because log groups with 0 storedBytes indicate no logs were written, not that there are too many. Option B is wrong because the retention policy does not prevent log creation. Option C is wrong because Lambda automatically creates log groups when logging is configured properly.
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 Lambda function is invoked too frequently, causing CloudWatch to throttle log ingestion.
Why it's wrong here
Throttling would cause partial logs, not zero bytes.
✗
The log group's retention policy of 7 days deletes logs immediately after creation.
Why it's wrong here
Retention policy deletes logs after 7 days, not immediately.
✓
The Lambda execution role lacks permissions to create log streams and put log events.
Why this is correct
Missing CloudWatch Logs permissions is a common cause of no logs.
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 Lambda function does not have a log group; the one shown belongs to another resource.
Why it's wrong here
The log group name matches the Lambda function naming convention.
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 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 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 Lambda execution role lacks permissions to create log streams and put log events. — Option D is correct because the Lambda function's execution role must have permissions to create log streams and put log events. Without these permissions, the function cannot write logs. Option A is wrong because log groups with 0 storedBytes indicate no logs were written, not that there are too many. Option B is wrong because the retention policy does not prevent log creation. Option C is wrong because Lambda automatically creates log groups when logging is configured properly.
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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