The answer is that the IAM policy is missing s3:ListBucket on the model bucket. When SageMaker creates an endpoint, it must first list the objects within the S3 bucket containing the model artifacts to locate and download the model data; without s3:ListBucket, the service cannot enumerate the bucket’s contents, even if s3:GetObject is granted. This question tests your understanding of the specific IAM permissions required for SageMaker endpoint creation on the AWS Certified Machine Learning Specialty MLS-C01 exam, where a common trap is confusing the permissions needed for inference (InvokeEndpoint) with those needed for deployment. The error occurs at creation time, not during invocation, so the missing ListBucket action is the culprit. Memory tip: think “List before Get” — SageMaker must see the bucket’s contents before it can grab the model files.
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.
Refer to the exhibit. A developer has this IAM policy attached to an IAM role used by SageMaker. When attempting to create an endpoint, the operation 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 policy is missing s3:ListBucket on the model bucket.
The policy grants permissions to create the model, endpoint config, and endpoint, but it does not include sagemaker:InvokeEndpoint (Option A). The error is likely due to missing sagemaker:InvokeEndpoint, but the question asks about creating an endpoint. Actually, creating an endpoint does not require InvokeEndpoint. The correct answer is that the policy is missing s3:ListBucket (Option B) because SageMaker needs to list objects in the bucket when accessing the model artifacts. Option C (ecr:DescribeRepositories) is not needed. Option D (sagemaker:DescribeEndpoint) is not required for creation.
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 is missing ecr:DescribeRepositories.
Why it's wrong here
DescribeRepositories is not required for pulling images.
✓
The policy is missing s3:ListBucket on the model bucket.
Why this is correct
SageMaker needs to list the bucket to access model artifacts.
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 is missing sagemaker:DescribeEndpoint.
Why it's wrong here
DescribeEndpoint is not needed for creation.
✗
The policy is missing sagemaker:InvokeEndpoint.
Why it's wrong here
InvokeEndpoint is for invoking, not creating.
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 policy is missing s3:ListBucket on the model bucket. — The policy grants permissions to create the model, endpoint config, and endpoint, but it does not include sagemaker:InvokeEndpoint (Option A). The error is likely due to missing sagemaker:InvokeEndpoint, but the question asks about creating an endpoint. Actually, creating an endpoint does not require InvokeEndpoint. The correct answer is that the policy is missing s3:ListBucket (Option B) because SageMaker needs to list objects in the bucket when accessing the model artifacts. Option C (ecr:DescribeRepositories) is not needed. Option D (sagemaker:DescribeEndpoint) is not required for creation.
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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