DEA-C01 Data Operations and Support Practice Question
This DEA-C01 practice question tests your understanding of data operations and support. 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 notices that a nightly AWS Glue ETL job has been failing for the past three days with the error 'Unable to locate credentials'. The job uses an IAM role for execution. What is the most likely cause of this 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.
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
The IAM role's trust policy does not include glue.amazonaws.com as a trusted entity.
The error 'Unable to locate credentials' indicates that the AWS Glue job cannot obtain AWS credentials to authenticate API calls. Since the job uses an IAM role for execution, the most likely cause is that the trust policy of that IAM role does not include 'glue.amazonaws.com' as a trusted entity. Without this trust relationship, AWS Glue cannot assume the role and thus has no credentials to sign requests.
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 IAM role does not have an access key attached.
Why it's wrong here
Glue jobs use IAM roles, not access keys.
✗
The S3 bucket name in the job parameters is misspelled.
Why it's wrong here
A misspelled bucket name would cause a different error, not a credentials error.
✓
The IAM role's trust policy does not include glue.amazonaws.com as a trusted entity.
Why this is correct
Without the trust policy, Glue cannot assume the role and gets 'Unable to locate credentials'.
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 JDBC connection string contains an incorrect password.
Why it's wrong here
The error is about credentials, not a password for a database connection.
Common exam traps
Common exam trap: answer the scenario, not the keyword
AWS often tests the distinction between IAM role trust policies (who can assume the role) and IAM role permission policies (what actions the role can perform), and candidates mistakenly focus on permission policies when the error is about credential acquisition.
Detailed technical explanation
How to think about this question
When AWS Glue runs an ETL job, it calls the STS AssumeRole API to obtain temporary credentials for the IAM role. The trust policy must explicitly grant 'sts:AssumeRole' permission to the Glue service principal ('glue.amazonaws.com'). If this is missing, the AssumeRole call fails, and the SDK throws the 'Unable to locate credentials' error. This is a common misconfiguration when creating cross-service IAM roles, especially when copying policies from other services like EC2 or Lambda.
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 Operations and Support — This question tests Data Operations and Support — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: The IAM role's trust policy does not include glue.amazonaws.com as a trusted entity. — The error 'Unable to locate credentials' indicates that the AWS Glue job cannot obtain AWS credentials to authenticate API calls. Since the job uses an IAM role for execution, the most likely cause is that the trust policy of that IAM role does not include 'glue.amazonaws.com' as a trusted entity. Without this trust relationship, AWS Glue cannot assume the role and thus has no credentials to sign requests.
What should I do if I get this DEA-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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