This MLS-C01 practice question tests your understanding of data engineering. Match the stated requirement to the specific cloud service, access model, or configuration option — many options are valid in isolation but not for this scenario. 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 IAM policy is attached to a data engineering team's role. The team needs to upload data to the 'confidential' prefix in the 'my-data-lake' bucket. However, they are receiving 'AccessDenied' errors. What is the likely cause?
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
The Deny statement with the condition explicitly denies access to the 'confidential' prefix for accounts other than 123456789012.
Option C is correct because the Deny statement explicitly denies access to the 'confidential' prefix when the request comes from an AWS account other than 123456789012. Since the data engineering team's role likely belongs to a different account, the Deny condition matches and overrides any Allow statements, resulting in an 'AccessDenied' error. In IAM, an explicit Deny always takes precedence over an Allow, so even if the Allow statement grants PutObject, the Deny blocks the upload.
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 condition in the Deny statement requires the team to use a specific source IP address.
Why it's wrong here
The condition uses aws:PrincipalAccount, not source IP.
✗
The Allow statement only grants GetObject and PutObject, but the team needs ListBucket.
Why it's wrong here
The error is AccessDenied for PutObject, which is allowed in the Allow statement, but the Deny overrides it.
✓
The Deny statement with the condition explicitly denies access to the 'confidential' prefix for accounts other than 123456789012.
Why this is correct
The Deny statement applies to all actions on the confidential prefix for accounts not matching 123456789012, overriding the Allow.
Related concept
Read the scenario before looking for a memorised answer.
✗
The Allow statement's resource does not include the 'confidential' prefix.
Why it's wrong here
The Allow statement includes all objects under my-data-lake, including confidential, but the Deny overrides.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The AWS exam often tests the principle that an explicit Deny overrides any Allow, and candidates mistakenly focus on the Allow statement's permissions (like missing ListBucket) instead of recognizing that the Deny statement with a condition is the root cause of the 'AccessDenied' error.
Detailed technical explanation
How to think about this question
IAM policy evaluation logic follows an 'explicit Deny wins' rule: if any policy (identity-based or resource-based) contains an explicit Deny that matches the request, the request is denied regardless of any Allow statements. The condition 'StringNotEquals' with 'aws:SourceAccount' is a common pattern to restrict cross-account access; here it denies any request where the source account is not 123456789012. In S3, the 's3:PutObject' action is sufficient to upload an object to a specific prefix; ListBucket is only needed for listing objects, not for uploading.
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.
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 Deny statement with the condition explicitly denies access to the 'confidential' prefix for accounts other than 123456789012. — Option C is correct because the Deny statement explicitly denies access to the 'confidential' prefix when the request comes from an AWS account other than 123456789012. Since the data engineering team's role likely belongs to a different account, the Deny condition matches and overrides any Allow statements, resulting in an 'AccessDenied' error. In IAM, an explicit Deny always takes precedence over an Allow, so even if the Allow statement grants PutObject, the Deny blocks the upload.
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.
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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