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.
A data engineer has attached the above IAM policy to an IAM role used by an AWS Glue ETL job. The job reads from and writes to 'my-data-bucket'. The job is failing 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 condition restricts access to a specific IP range that does not include the AWS Glue service IPs.
The IAM policy includes a condition that restricts access to requests originating from a specific IP address range. AWS Glue ETL jobs run on ephemeral compute resources that use a dynamic pool of IP addresses, which are not guaranteed to fall within any fixed customer-managed IP range. Therefore, the condition causes the Access Denied error because the Glue service IPs are not within the allowed range.
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 restricts access to a specific IP range that does not include the AWS Glue service IPs.
Why this is correct
The condition requires the request source IP to be in 10.0.0.0/24, but Glue's IPs are different.
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 IAM role needs to have s3:ListBucket permission.
Why it's wrong here
While ListBucket may be needed, the immediate error is likely due to the IP condition.
✗
The IAM role does not have permission to list the bucket.
Why it's wrong here
The policy allows GetObject and PutObject, but not ListBucket, which might be needed for listing objects.
✗
The resource ARN should include the bucket itself, not just the objects.
Why it's wrong here
The bucket ARN is missing for bucket-level operations, but the error is Access Denied, not a policy syntax issue.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates assume the IAM policy is missing a permission like s3:ListBucket, but the real issue is the IP condition that inadvertently blocks the Glue service because its source IPs are not within the specified range.
Detailed technical explanation
How to think about this question
AWS Glue ETL jobs run on Apache Spark executors that use Elastic Network Interfaces (ENIs) with IP addresses from AWS's internal pool, not from a customer's VPC unless explicitly configured with a VPC endpoint. The condition key 'aws:SourceIp' evaluates the source IP of the request, but Glue jobs do not have a fixed source IP; they use service-owned IPs that vary per job run. In practice, if you need to restrict access by network, you should use a VPC endpoint with a condition on 'aws:SourceVpce' or 'aws:SourceVpc' instead of IP-based conditions.
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 condition restricts access to a specific IP range that does not include the AWS Glue service IPs. — The IAM policy includes a condition that restricts access to requests originating from a specific IP address range. AWS Glue ETL jobs run on ephemeral compute resources that use a dynamic pool of IP addresses, which are not guaranteed to fall within any fixed customer-managed IP range. Therefore, the condition causes the Access Denied error because the Glue service IPs are not within the allowed range.
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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