The answer is the S3 lifecycle policy expiring objects after 30 days, which removes the input data the Glue ETL job expects. This is correct because the lifecycle rule deletes objects from the source bucket once they reach the specified age, and when the Glue job runs again, it cannot find the required input files, causing the “Input data not found” error. On the AWS Certified Machine Learning Specialty MLS-C01 exam, this scenario tests your understanding of how S3 lifecycle policies can directly affect Glue ETL data pipelines, often appearing as a trap where candidates overlook the interaction between storage lifecycle rules and job execution timing. A common mistake is to blame job bookmarks or temporary directories, but the root cause is always the lifecycle action removing source data before the job reads it. Memory tip: if a Glue job fails after a set number of days, always check the S3 lifecycle expiration first—data gone means job broken.
MLS-C01 Data Engineering Practice Question
This MLS-C01 practice question tests your understanding of data engineering. 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
Refer to the exhibit. A data engineer has deployed this CloudFormation template. The Glue job 'my-etl-job' reads from the S3 bucket 'my-data-lake-bucket' and writes transformed data to another bucket. After 30 days, the data engineer notices that the Glue job fails with 'Input data not found' errors. 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 lifecycle configuration deletes objects from the bucket after 30 days, removing the input data.
Option A is correct. The lifecycle rule expires objects after 30 days, removing the input data that the Glue job expects. Option B is incorrect because job bookmarks track state but do not cause data loss. Option C is incorrect because the temp directory is separate. Option D is incorrect because the script location is not affected by the lifecycle rule.
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 temporary directory 'my-temp-dir' is being cleaned up by the lifecycle configuration.
Why it's wrong here
The temp directory is not in the same bucket; it's in a different bucket.
✗
The script location 's3://my-scripts/etl.py' is being deleted by the lifecycle rule.
Why it's wrong here
The script is in a different bucket, not affected by this lifecycle rule.
✗
The job bookmark option 'job-bookmark-enable' is causing the job to skip newly arriving data.
Why it's wrong here
Job bookmarks track processed data but do not cause data loss.
✓
The lifecycle configuration deletes objects from the bucket after 30 days, removing the input data.
Why this is correct
The ExpirationInDays: 30 rule deletes objects older than 30 days, which may include input data.
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.
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 MLS-C01 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.
Data Engineering — This question tests Data Engineering — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: The lifecycle configuration deletes objects from the bucket after 30 days, removing the input data. — Option A is correct. The lifecycle rule expires objects after 30 days, removing the input data that the Glue job expects. Option B is incorrect because job bookmarks track state but do not cause data loss. Option C is incorrect because the temp directory is separate. Option D is incorrect because the script location is not affected by the lifecycle rule.
What should I do if I get this MLS-C01 question wrong?
Identify which MLS-C01 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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