Required IAM Permissions for SageMaker Training Jobs Using Custom ECR Images
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. An administrator has attached this IAM policy to a user. The user tries to start a SageMaker training job that uses a custom Docker image from Amazon ECR. The training job fails with an access denied error. What is the MOST likely reason?
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 ecr:GetDownloadUrlForLayer and ecr:BatchGetImage.
The IAM policy grants sagemaker:* and s3:* actions but does not include the specific ECR permissions required to pull a custom Docker image. When SageMaker launches a training job with a custom image, it needs ecr:GetDownloadUrlForLayer and ecr:BatchGetImage to authenticate and download the image layers from Amazon ECR. Without these permissions, the training job fails with 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 s3:* action is too permissive and should be scoped.
Why it's wrong here
Overly permissive S3 policy is not causing the failure.
✓
The policy is missing ecr:GetDownloadUrlForLayer and ecr:BatchGetImage.
Why this is correct
ECR permissions are required to pull the custom image.
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:PassRole permission is missing the SageMaker service principal.
Why it's wrong here
The PassRole is allowed for the specific role.
✗
The sagemaker:* action should be restricted to specific resources.
Why it's wrong here
SageMaker actions are allowed, but ECR is missing.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates assume full sagemaker:* and s3:* permissions are sufficient, overlooking the specific ECR permissions required when using a custom Docker image from a private repository.
Detailed technical explanation
How to think about this question
SageMaker training jobs that use custom Docker images from Amazon ECR require the ECR authorization token (via ecr:GetAuthorizationToken) and the ability to download image layers (ecr:GetDownloadUrlForLayer and ecr:BatchGetImage). The ecr:GetDownloadUrlForLayer action provides a pre-signed URL for each layer blob, while ecr:BatchGetImage retrieves the image manifest. Without these, the SageMaker service cannot pull the image, even if the IAM user has full SageMaker and S3 permissions.
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.
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 ecr:GetDownloadUrlForLayer and ecr:BatchGetImage. — The IAM policy grants sagemaker:* and s3:* actions but does not include the specific ECR permissions required to pull a custom Docker image. When SageMaker launches a training job with a custom image, it needs ecr:GetDownloadUrlForLayer and ecr:BatchGetImage to authenticate and download the image layers from Amazon ECR. Without these permissions, the training job fails with 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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Question Discussion
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