The answer is the IAM role used by the crawler lacks the kms:Decrypt permission for the KMS key encrypting the new partitions. When an S3 bucket uses server-side encryption with AWS KMS (SSE-KMS), the Glue crawler must have explicit decrypt rights to read the object metadata and schema; without this permission, the crawler cannot list or detect partitions in encrypted prefixes, even if the data is present. On the AWS Certified Data Engineer Associate DEA-C01 exam, this scenario tests your understanding of how encryption permissions intersect with Glue’s partition discovery process—a common trap is assuming S3 events or crawler configuration limits are the issue, when the real blocker is KMS authorization. Remember the mnemonic: “No Decrypt, No Detect” to recall that SSE-KMS partitions require kms:Decrypt on the crawler’s IAM role before any partition detection can occur.
DEA-C01 Data Operations and Support Practice Question
This DEA-C01 practice question tests your understanding of data operations and support. This is a configuration task: choose the command set that satisfies every stated requirement. Small differences — like 'secret' vs 'password' or 'transport input ssh' vs 'all' — change whether the answer is correct. 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 company uses Amazon S3 to store raw data files. An AWS Glue crawler creates metadata in the Data Catalog. The data engineer discovers that the crawler is not detecting new partitions after new data is added to the S3 bucket. 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 IAM role used by the crawler does not have kms:Decrypt permission for the KMS key that encrypts the new partitions.
Option B is correct because if the S3 bucket uses an SSE-KMS encrypted prefix, the crawler may not have permission to decrypt; the KMS key policy or IAM role must allow kms:Decrypt. Option A is wrong because S3 events are not required for crawling. Option C is wrong because the crawler can handle many objects. Option D is wrong because the crawler configuration may need to be set to detect partitions, but the most likely cause given encryption is permission.
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 IAM role used by the crawler does not have kms:Decrypt permission for the KMS key that encrypts the new partitions.
Why this is correct
Without decrypt permission, the crawler cannot read the 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.
✗
The crawler configuration has 'Crawl all folders' disabled.
Why it's wrong here
If disabled, crawler would not crawl any new folders, but the issue is specifically with new partitions.
✗
The S3 bucket has too many objects, exceeding the crawler's limit.
Why it's wrong here
Crawlers can handle millions of objects.
✗
The crawler does not have S3 event notifications enabled.
Why it's wrong here
Crawlers do not rely on event notifications; they scan the bucket.
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 DEA-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 Operations and Support — This question tests Data Operations and Support — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: The IAM role used by the crawler does not have kms:Decrypt permission for the KMS key that encrypts the new partitions. — Option B is correct because if the S3 bucket uses an SSE-KMS encrypted prefix, the crawler may not have permission to decrypt; the KMS key policy or IAM role must allow kms:Decrypt. Option A is wrong because S3 events are not required for crawling. Option C is wrong because the crawler can handle many objects. Option D is wrong because the crawler configuration may need to be set to detect partitions, but the most likely cause given encryption is permission.
What should I do if I get this DEA-C01 question wrong?
Identify which DEA-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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