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.
An IAM policy attached to a SageMaker notebook role is shown. The data engineer tries to run an Athena query on a table in the 'my_database' Glue database. The query fails with an access denied error. 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.
The policy does not allow s3:PutObject on the query results location.
Why wrong: This option suggests that the missing permission is s3:PutObject on the query results location. While Athena does need to write query results to S3, the immediate error here is caused by the lack of permission to execute the query itself, not by the S3 write. The policy might or might not include S3 permissions, but the missing athena:StartQueryExecution is the primary cause.
B
The policy does not allow glue:GetTable on the specific database.
Why wrong: This option suggests the missing permission is glue:GetTable on the specific database. While Glue permissions are necessary to access table metadata, the error message indicates that the query execution failed due to access denied on Athena, not Glue. Even if Glue permissions are present, Athena still requires the StartQueryExecution action.
C
The policy does not allow athena:StartQueryExecution on the Athena workgroup.
Correct because the IAM policy lacks the `athena:StartQueryExecution` action on the specific workgroup. This action is required to initiate an Athena query. Without it, any attempt to run a query will result in an access denied error, regardless of other permissions.
D
The policy does not allow s3:ListBucket on the bucket.
Why wrong: This option suggests the missing permission is s3:ListBucket on the bucket. Listing the bucket is not a prerequisite for running an Athena query. The error is directly related to Athena's execution permission, not S3 list operations.
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
The policy does not allow athena:StartQueryExecution on the Athena workgroup.
Option C is correct because the IAM policy does not include the `athena:StartQueryExecution` action on the Athena workgroup, which is required to submit a query. Even if the role has permissions for Glue and S3, Athena will deny the request if the workgroup-level permission to start queries is missing, resulting in an access denied error.
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 policy does not allow s3:PutObject on the query results location.
Why it's wrong here
This option suggests that the missing permission is s3:PutObject on the query results location. While Athena does need to write query results to S3, the immediate error here is caused by the lack of permission to execute the query itself, not by the S3 write. The policy might or might not include S3 permissions, but the missing athena:StartQueryExecution is the primary cause.
✗
The policy does not allow glue:GetTable on the specific database.
Why it's wrong here
This option suggests the missing permission is glue:GetTable on the specific database. While Glue permissions are necessary to access table metadata, the error message indicates that the query execution failed due to access denied on Athena, not Glue. Even if Glue permissions are present, Athena still requires the StartQueryExecution action.
✓
The policy does not allow athena:StartQueryExecution on the Athena workgroup.
Why this is correct
Correct because the IAM policy lacks the `athena:StartQueryExecution` action on the specific workgroup. This action is required to initiate an Athena query. Without it, any attempt to run a query will result in an access denied error, regardless of other permissions.
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 policy does not allow s3:ListBucket on the bucket.
Why it's wrong here
This option suggests the missing permission is s3:ListBucket on the bucket. Listing the bucket is not a prerequisite for running an Athena query. The error is directly related to Athena's execution permission, not S3 list operations.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates assume the error is due to missing S3 or Glue permissions because the query accesses those services, but the actual missing permission is the Athena-specific action required to initiate the query execution.
Detailed technical explanation
How to think about this question
Athena uses workgroups to isolate queries and control costs; each workgroup can have its own IAM policy that must explicitly allow `athena:StartQueryExecution`. Without this permission, the API call to submit the query is rejected before any Glue or S3 operations are attempted. In practice, this often occurs when a policy grants broad Glue and S3 access but omits the specific Athena action, leading to a misleading 'access denied' error that seems unrelated to Athena itself.
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 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.
Quick reference
AWS S3 Storage Class Comparison
Storage Class
Min Duration
Retrieval
Use Case
S3 Standard
None
Immediate
Frequently accessed data
S3 Standard-IA
30 days
Immediate
Infrequent access, rapid retrieval
S3 One Zone-IA
30 days
Immediate
Non-critical infrequent data
S3 Intelligent-Tiering
None
Immediate–hours
Unknown or changing access patterns
S3 Glacier Instant
90 days
Milliseconds
Archive with instant retrieval
S3 Glacier Flexible
90 days
Minutes–hours
Archive, flexible retrieval
S3 Glacier Deep Archive
180 days
Hours
Long-term compliance archive
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.
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 policy does not allow athena:StartQueryExecution on the Athena workgroup. — Option C is correct because the IAM policy does not include the `athena:StartQueryExecution` action on the Athena workgroup, which is required to submit a query. Even if the role has permissions for Glue and S3, Athena will deny the request if the workgroup-level permission to start queries is missing, resulting in an access denied error.
What should I do if I get this MLS-C01 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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