The correct answer is that the IAM policy is missing the s3:ListBucket permission, which causes the SageMaker training job to fail with an access denied error. While the policy grants s3:GetObject to read individual training objects, SageMaker must first list the bucket’s contents to discover and access those objects, and without s3:ListBucket, the service cannot enumerate the data location. On the AWS Certified Machine Learning Specialty MLS-C01 exam, this scenario tests your understanding of how SageMaker interacts with S3 during job creation—a common trap is assuming GetObject alone suffices for reading training data. Remember that listing is a prerequisite for getting: SageMaker needs to see the bucket’s structure before it can fetch files. A useful memory tip is “List before Get”—think of it as needing a directory listing before you can pick a file off the shelf.
MLS-C01 Practice Question: Machine Learning Implementation and Operations
This MLS-C01 practice question tests your understanding of machine learning implementation and operations. 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.
A data scientist attempts to create a SageMaker training job using the IAM policy shown in the exhibit. The training job 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.
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
The IAM policy is missing the s3:ListBucket action
Option C is correct: The policy allows s3:GetObject but not s3:ListBucket, which is required to read objects. Option A (missing sagemaker:DescribeTrainingJob) is not needed for creation. Option B (resource arn for s3 is wrong) is correct but not the cause of access denied. Option D (missing s3:PutObject) is not required for reading training data.
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 S3 bucket policy does not grant access to the SageMaker service principal
Why it's wrong here
The error is from the IAM role, not bucket policy.
✗
The IAM policy is missing the sagemaker:DescribeTrainingJob permission
Why it's wrong here
Describe is not needed to create a job.
✓
The IAM policy is missing the s3:ListBucket action
Why this is correct
SageMaker needs ListBucket to read objects from the bucket.
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 IAM policy is missing the s3:PutObject permission
Why it's wrong here
PutObject is for writing, not reading training data.
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.
Machine Learning Implementation and Operations — This question tests Machine Learning Implementation and Operations — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: The IAM policy is missing the s3:ListBucket action — Option C is correct: The policy allows s3:GetObject but not s3:ListBucket, which is required to read objects. Option A (missing sagemaker:DescribeTrainingJob) is not needed for creation. Option B (resource arn for s3 is wrong) is correct but not the cause of access denied. Option D (missing s3:PutObject) is not required for reading training data.
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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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.
Question Discussion
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