Quick Answer
The answer is the object's last modified timestamp, which is the correct choice because the AWS CLI s3 head-object command returns metadata including the LastModified field, allowing a direct comparison with the Glue ETL job completion time to determine if the file was altered after processing. This command retrieves key object properties without downloading the file, and the LastModified timestamp serves as a reliable indicator of when the object was last changed. On the AWS Certified Machine Learning Specialty MLS-C01 exam, this tests your understanding of S3 object metadata and how to efficiently audit data freshness in ML pipelines—a common scenario where engineers must verify that source data hasn't been updated since a transformation job ran. A frequent trap is confusing head-object with list-objects or assuming it returns only size or ETag, but remember that LastModified is the critical field for temporal comparisons. Memory tip: "Head for the date" — when you need to know when an object changed, head-object gives you the timestamp.
This MLS-C01 practice question tests your understanding of data engineering. Examine the command output carefully: the correct answer depends on what the output actually shows, not on general recall alone. 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 data engineer runs the AWS CLI command above to inspect a file in S3. They need to determine if the file was modified after a Glue ETL job processed it. What additional information could they obtain from this command?
The object's content type.
Why wrong: Content type is not shown in this output.
The object's storage class.
Why wrong: Storage class is not included in the output of head-object unless requested.
The object's last modified timestamp.
The LastModified field indicates when the object was last modified.
The object's ETag.
Why wrong: ETag is shown but does not help determine modification time.
Answer choices
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
The object's last modified timestamp.
Option D is correct because the LastModified timestamp is provided, which can be used to compare with job completion time. Option A is wrong because head-object does not show object size. Option B is wrong because ContentLength is shown. Option C is wrong because ETag is shown.
Key principle: Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Answer analysis
For each option: why learners choose it and why it is or isn't the right answer here.
The object's content type.
Why it's wrong here
Content type is not shown in this output.
The object's storage class.
Why it's wrong here
Storage class is not included in the output of head-object unless requested.
The object's last modified timestamp.
Why this is correct
The LastModified field indicates when the object was last modified.
Related concept
Read the scenario before looking for a memorised answer.
The object's ETag.
Why it's wrong here
ETag is shown but does not help determine modification time.
Common exam traps
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.
Trap categories for this question
Command / output trap
Content type is not shown in this output.
Detailed technical explanation
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.
Key takeaway
Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Real-world example
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
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.
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FAQ
Data Engineering — This question tests Data Engineering — Read the scenario before looking for a memorised answer..
The correct answer is: The object's last modified timestamp. — Option D is correct because the LastModified timestamp is provided, which can be used to compare with job completion time. Option A is wrong because head-object does not show object size. Option B is wrong because ContentLength is shown. Option C is wrong because ETag is shown.
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.
Read the scenario before looking for a memorised answer.
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Last reviewed: Jun 20, 2026
This MLS-C01 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 MLS-C01 exam.
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