This MLS-C01 practice question tests your understanding of modeling. 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. The training job 'my-job' failed with the error 'Unable to pull image from ECR'. 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 does not have permission to pull images from the ECR repository.
The error 'Unable to pull image from ECR' indicates that the SageMaker training job could not retrieve the custom Docker image stored in Amazon ECR. The most likely cause is that the IAM role associated with the training job lacks the `ecr:GetDownloadUrlForLayer` and `ecr:BatchGetImage` permissions required to pull images from the ECR repository. Without these permissions, SageMaker cannot authenticate and download the container image, even if the repository and image exist.
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 does not have permission to pull images from the ECR repository.
Why this is correct
Without ecr:GetDownloadUrlForLayer and BatchGetImage, the pull fails.
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 instance type ml.m5.large does not support custom images.
Why it's wrong here
Custom images are supported on all instance types.
✗
The S3 bucket for training data is in a different account.
Why it's wrong here
The error is about ECR, not S3.
✗
The role ARN is incorrect.
Why it's wrong here
The ARN appears valid.
Common exam traps
Common exam trap: answer the scenario, not the keyword
Cisco often tests the misconception that any IAM role with basic SageMaker permissions can pull images from ECR, but the trap here is that the role must have explicit ECR permissions (not just SageMaker permissions) to download the container image, and candidates may incorrectly blame the instance type or S3 bucket location instead.
Detailed technical explanation
How to think about this question
When SageMaker pulls a custom image from ECR, it uses the `GetAuthorizationToken` API to obtain a temporary password, then authenticates with the registry using Docker login. The IAM role must have a policy granting `ecr:GetAuthorizationToken`, `ecr:BatchGetImage`, and `ecr:GetDownloadUrlForLayer` for the specific repository. A common subtlety is that the ECR repository must be in the same AWS account as the SageMaker training job, unless cross-account access is explicitly configured via a repository policy or IAM role trust relationship. Additionally, if the image is stored in a different region, the job's VPC or internet access must allow outbound HTTPS traffic to the ECR endpoint.
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.
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.
Modeling — This question tests Modeling — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: The IAM role does not have permission to pull images from the ECR repository. — The error 'Unable to pull image from ECR' indicates that the SageMaker training job could not retrieve the custom Docker image stored in Amazon ECR. The most likely cause is that the IAM role associated with the training job lacks the `ecr:GetDownloadUrlForLayer` and `ecr:BatchGetImage` permissions required to pull images from the ECR repository. Without these permissions, SageMaker cannot authenticate and download the container image, even if the repository and image exist.
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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