This MLS-C01 practice question tests your understanding of data engineering. 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.
Network Topology
A data engineer runs the CLI command to download an object from S3. The bucket owner is 123456789012, and the engineer's IAM user has s3:GetObject permission on the bucket. The object was uploaded by a different AWS account. What is the MOST likely reason for the AccessDenied error?
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.
Network Topology
A
The --expected-bucket-owner parameter is incorrect
Why wrong: The parameter is for bucket owner, not object owner.
B
The object is owned by a different AWS account, and the bucket owner has not been granted access
Object ACLs or bucket policy must grant access to bucket owner.
C
The bucket policy denies access to the engineer's IAM user
Why wrong: There is no indication of a Deny.
D
The IAM policy does not allow s3:GetObject for that specific key
Why wrong: The policy allows GetObject on the bucket, but object ownership matters.
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
The object is owned by a different AWS account, and the bucket owner has not been granted access
Option B is correct because when an object is uploaded to S3 by a different AWS account, the object is owned by the uploading account, not the bucket owner. By default, the bucket owner does not have access to objects uploaded by other accounts, even if the bucket owner has a policy granting s3:GetObject to their IAM users. The engineer's IAM user has permission on the bucket, but the object itself is not owned by the bucket owner, so the bucket owner cannot delegate access to it unless the object owner explicitly grants read access via an object ACL or a bucket policy that the object owner accepts.
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 --expected-bucket-owner parameter is incorrect
Why it's wrong here
The parameter is for bucket owner, not object owner.
✓
The object is owned by a different AWS account, and the bucket owner has not been granted access
Why this is correct
Object ACLs or bucket policy must grant access to bucket owner.
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 policy denies access to the engineer's IAM user
Why it's wrong here
There is no indication of a Deny.
✗
The IAM policy does not allow s3:GetObject for that specific key
Why it's wrong here
The policy allows GetObject on the bucket, but object ownership matters.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates assume bucket-level permissions (like s3:GetObject on the bucket) automatically grant access to all objects in the bucket, but S3's object ownership model requires explicit permission from the object owner for objects uploaded by other accounts.
Detailed technical explanation
How to think about this question
Under the hood, S3 object ownership is separate from bucket ownership. When an object is uploaded by a different AWS account, the object's ACL defaults to 'bucket-owner-full-control' only if the uploading account explicitly sets it; otherwise, the bucket owner has no access. This is governed by the S3 Object Ownership setting (e.g., 'BucketOwnerEnforced' or 'BucketOwnerPreferred'), which can override this behavior if enabled. In real-world scenarios, this often occurs in cross-account data lakes where the bucket owner must enable 'BucketOwnerEnforced' or request the uploading account to grant 'bucket-owner-full-control' via ACLs.
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.
Visual reference
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.
Data Engineering — This question tests Data Engineering — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: The object is owned by a different AWS account, and the bucket owner has not been granted access — Option B is correct because when an object is uploaded to S3 by a different AWS account, the object is owned by the uploading account, not the bucket owner. By default, the bucket owner does not have access to objects uploaded by other accounts, even if the bucket owner has a policy granting s3:GetObject to their IAM users. The engineer's IAM user has permission on the bucket, but the object itself is not owned by the bucket owner, so the bucket owner cannot delegate access to it unless the object owner explicitly grants read access via an object ACL or a bucket policy that the object owner accepts.
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.