The answer is that the IAM role associated with the Glue job lacks the necessary write permissions to the RDS instance. This is because AWS Glue ETL jobs assume an IAM role to interact with other AWS services; when the job attempts to write to an RDS MySQL database, the role must include a policy allowing the `rds-db:connect` action and the database user must have been granted write privileges on the target tables. On the AWS Certified Data Engineer Associate DEA-C01 exam, this scenario tests your understanding of how IAM roles govern cross-service access, and a common trap is to overlook that RDS requires both an IAM policy for network connectivity and database-level GRANTs for actual data operations. Remember the two-layer rule: IAM for the door, SQL GRANTs for the room.
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 is troubleshooting a failed AWS Glue ETL job. The job reads from an S3 bucket and writes to an RDS MySQL database. The job fails with an 'Access Denied' error when trying to write to RDS. 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 IAM role associated with the Glue job does not have the necessary permissions to write to the RDS instance.
The error 'Access Denied' when writing to RDS indicates that the AWS Glue job's IAM role lacks the necessary permissions (e.g., rds-db:connect, or specific database-level GRANTs) to perform write operations on the RDS MySQL instance. AWS Glue uses the attached IAM role to authenticate and authorize actions against AWS services, and without proper IAM policies allowing access to the RDS resource, the write attempt is denied.
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 associated with the Glue job does not have the necessary permissions to write to the RDS instance.
Why this is correct
IAM role needs RDS write permissions.
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 Glue job is running in a VPC without a route to the internet.
Why it's wrong here
Would cause timeout, not access denied.
✗
The S3 bucket policy does not allow the Glue job to read the data.
Why it's wrong here
Error is on write to RDS, not read from S3.
✗
The RDS instance is encrypted with a KMS key that the Glue job cannot access.
Why it's wrong here
Would cause decryption error, not access denied.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates often confuse network connectivity issues (Option B) with authorization errors, but 'Access Denied' is a specific HTTP 403 error indicating lack of permissions, not a network problem.
Detailed technical explanation
How to think about this question
Under the hood, AWS Glue jobs assume an IAM role that must include a trust policy allowing Glue to assume it, and the role's permissions must include actions like rds-db:connect for the specific RDS resource ARN. Additionally, for MySQL, the database user must have GRANT permissions (e.g., INSERT, UPDATE) on the target tables; if the IAM role maps to a database user with insufficient privileges, the 'Access Denied' error can also occur at the database level, not just the AWS API level.
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 associated with the Glue job does not have the necessary permissions to write to the RDS instance. — The error 'Access Denied' when writing to RDS indicates that the AWS Glue job's IAM role lacks the necessary permissions (e.g., rds-db:connect, or specific database-level GRANTs) to perform write operations on the RDS MySQL instance. AWS Glue uses the attached IAM role to authenticate and authorize actions against AWS services, and without proper IAM policies allowing access to the RDS resource, the write attempt is denied.
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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