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.
Exhibit
Refer to the exhibit.
```
Training job status: Failed
Error: ClientError: Data download failed.
The downloaded file size (0 bytes) does not match expected size (1024 bytes).
Check that the S3 object exists and is readable.
```
A data scientist runs a SageMaker training job that fails with the above error. The S3 bucket and object exist, and the IAM role has s3:GetObject permission. 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.
Refer to the exhibit.
```
Training job status: Failed
Error: ClientError: Data download failed.
The downloaded file size (0 bytes) does not match expected size (1024 bytes).
Check that the S3 object exists and is readable.
```
A
The S3 object was uploaded with incorrect checksum or is corrupted
A corrupted file can cause size mismatch and zero-byte download.
B
The training instance does not have internet access
Why wrong: SageMaker uses VPC endpoints or internet; lack of internet would cause timeout, not size mismatch.
C
The S3 bucket has versioning enabled and the object version is not specified
Why wrong: If versioning is enabled, SageMaker uses latest version unless specified; would not cause zero bytes.
D
The IAM role lacks kms:Decrypt permission for an encrypted S3 object
Why wrong: Missing KMS permission would cause access denied, not size mismatch.
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
The S3 object was uploaded with incorrect checksum or is corrupted
The error indicates that SageMaker cannot read the S3 object, even though the bucket and object exist and the IAM role has s3:GetObject permission. The most likely cause is that the object was uploaded with an incorrect checksum or is corrupted, which prevents SageMaker from verifying the integrity of the data during the training job initialization. SageMaker uses ETag (MD5 checksum) validation when reading objects, and a mismatch triggers a failure.
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 object was uploaded with incorrect checksum or is corrupted
Why this is correct
A corrupted file can cause size mismatch and zero-byte download.
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 training instance does not have internet access
Why it's wrong here
SageMaker uses VPC endpoints or internet; lack of internet would cause timeout, not size mismatch.
✗
The S3 bucket has versioning enabled and the object version is not specified
Why it's wrong here
If versioning is enabled, SageMaker uses latest version unless specified; would not cause zero bytes.
✗
The IAM role lacks kms:Decrypt permission for an encrypted S3 object
Why it's wrong here
Missing KMS permission would cause access denied, not size mismatch.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates often assume permission or network issues are the root cause, but the error specifically points to a data integrity problem, which is a subtle but critical detail in SageMaker's S3 interaction.
Detailed technical explanation
How to think about this question
SageMaker training jobs use the S3 GetObject API with an If-Match header containing the ETag (MD5 hash) to ensure data integrity. If the uploaded object's checksum does not match the ETag stored in S3 (e.g., due to a partial upload or network corruption), the request fails with a 412 Precondition Failed error. This is a common issue when using multipart uploads or when the object is modified after upload without updating the ETag.
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 S3 object was uploaded with incorrect checksum or is corrupted — The error indicates that SageMaker cannot read the S3 object, even though the bucket and object exist and the IAM role has s3:GetObject permission. The most likely cause is that the object was uploaded with an incorrect checksum or is corrupted, which prevents SageMaker from verifying the integrity of the data during the training job initialization. SageMaker uses ETag (MD5 checksum) validation when reading objects, and a mismatch triggers a failure.
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.
About these practice questions
Courseiva creates original exam-style practice questions with explanations and wrong-answer analysis. It does not publish real exam questions, exam dumps, or protected exam content. Learn why practice questions differ from exam dumps →
Share a tip, memory trick, or ask about the reasoning behind this question. Do not post real exam questions, leaked content, braindumps, or copyrighted exam material. Comments are moderated and may be removed without notice.
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
Share a tip, memory trick, or ask about the reasoning behind this question. Do not post real exam questions, leaked content, braindumps, or copyrighted exam material. Comments are moderated and may be removed without notice.
Sign in to join the discussion.