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. A data scientist wants to use SageMaker to train a model using data stored in 'my-bucket'. 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 training job is not requesting server-side encryption with AES256
Option C is correct because SageMaker training jobs require server-side encryption with AES256 when the S3 bucket uses default encryption with AES256. If the training job does not explicitly request SSE-S3 (AES256) in its S3 data source configuration, the S3 service denies access, resulting in an 'access denied' error even if the IAM role has full S3 permissions.
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 bucket uses AWS KMS key encryption instead of AES256
Why it's wrong here
The policy explicitly allows AES256; if KMS is used, the condition would fail.
✗
The bucket name in the policy does not match the actual bucket name
Why it's wrong here
The policy seems correct; the error is likely due to encryption requirements.
✓
The training job is not requesting server-side encryption with AES256
Why this is correct
The policy denies PutObject if encryption is not AES256, so the job must include the encryption header.
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 bucket is publicly accessible but the IAM role lacks permissions
Why it's wrong here
The policy is correctly attached; the issue is the encryption header.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates often assume 'access denied' always means an IAM permissions issue, but AWS S3 can return 'Access Denied' for encryption policy violations when the request does not match the bucket's default encryption settings.
Detailed technical explanation
How to think about this question
SageMaker training jobs use the `S3DataSource` parameter with an `S3Uri` and an optional `S3DataType`. When the bucket has default encryption set to AES256, the training job must include `ServerSideEncryption: 'AES256'` in the S3 data source configuration; otherwise, S3 rejects the request with an 'Access Denied' error because the default encryption policy requires explicit encryption headers. This behavior is documented in the AWS S3 developer guide under 'Using Server-Side Encryption with Amazon S3'.
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 training job is not requesting server-side encryption with AES256 — Option C is correct because SageMaker training jobs require server-side encryption with AES256 when the S3 bucket uses default encryption with AES256. If the training job does not explicitly request SSE-S3 (AES256) in its S3 data source configuration, the S3 service denies access, resulting in an 'access denied' error even if the IAM role has full S3 permissions.
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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