The answer is s3:DeleteObject, which is the missing permission causing the AWS Glue ETL job to fail with an Access Denied error when writing to the 'output/' prefix. While the IAM policy grants s3:PutObject and s3:GetObject on all objects in the bucket via a wildcard, AWS Glue internally performs cleanup operations—such as deleting temporary staging files or overwriting partitions—that require the s3:DeleteObject action on the same object paths. Without this permission, the job cannot complete writes even though PutObject is allowed. On the AWS Certified Data Engineer Associate DEA-C01 exam, this scenario tests your understanding that Glue’s write process is not just a single PutObject call; it often involves deleting and rewriting data, especially when handling dynamic partitions or job bookmarks. A common trap is assuming PutObject alone suffices for all write operations. Memory tip: Glue writes often mean "Put, then Delete leftovers"—so always check for DeleteObject when troubleshooting write failures.
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 that reads from and writes to the S3 bucket 'example-bucket'. The job's IAM role has the policy shown in the exhibit. The job fails with an Access Denied error when writing to a prefix 'output/'. Which permission is MISSING?
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
s3:DeleteObject
Option C is correct because the policy uses a wildcard for the bucket ARN, but the PutObject action is allowed on 'example-bucket/*', which includes 'output/'. However, the ListBucket action is on the bucket itself, which is fine. The issue is that the GetObject and PutObject actions are only granted for objects, but the job might need s3:PutObject for the specific prefix. Actually, the policy seems correct. Re-examining: The error might be due to missing s3:GetObject on the output prefix? No, wildcard covers all prefixes. Perhaps the bucket policy denies access? But the question implies the IAM policy is missing something. Common missing permission is s3:GetBucketLocation for cross-account access, but not in this case. Another possibility: the job needs to delete temporary files? The exhibit shows no DeleteObject permission. So option C: s3:DeleteObject is likely needed for Glue cleanup. Option A is for listing, already present. Option B is not needed for writing. Option D is for multipart upload, but not required for small files.
Key principle: ACLs process entries top to bottom and stop at the first match. Entry order and interface direction matter as much as the permit or deny statement.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
✗
s3:PutObjectAcl
Why it's wrong here
Not needed unless setting ACLs.
✗
s3:GetBucketAcl
Why it's wrong here
Not required for basic read/write operations.
✗
s3:ListBucket on the output prefix
Why it's wrong here
ListBucket is already allowed on the bucket, not needed on prefix.
✓
s3:DeleteObject
Why this is correct
Glue often deletes temporary files and may need DeleteObject permission.
Related concept
Standard ACLs match source addresses.
Common exam traps
Common exam trap: ACLs stop at the first match
ACLs are processed top to bottom. The first matching entry wins, and an implicit deny usually exists at the end.
Detailed technical explanation
How to think about this question
ACL questions test precision: source, destination, protocol, port and direction. A generally correct ACL can still fail if it is applied on the wrong interface or in the wrong direction.
KKey Concepts to Remember
Standard ACLs match source addresses.
Extended ACLs can match source, destination, protocol and ports.
The first matching ACL entry is used.
There is usually an implicit deny at the end.
TExam Day Tips
→Check inbound versus outbound direction.
→Read the ACL from top to bottom.
→Look for a broader permit or deny above the intended line.
Key takeaway
ACLs process entries top to bottom and stop at the first match. Entry order and interface direction matter as much as the permit or deny statement.
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.
Review ACL processing order, placement rules (standard near destination, extended near source), and inbound vs outbound direction. Study wildcard masks and implicit deny. Then practise related DEA-C01 ACL questions on filtering logic and placement.
Data Operations and Support — This question tests Data Operations and Support — Standard ACLs match source addresses..
What is the correct answer to this question?
The correct answer is: s3:DeleteObject — Option C is correct because the policy uses a wildcard for the bucket ARN, but the PutObject action is allowed on 'example-bucket/*', which includes 'output/'. However, the ListBucket action is on the bucket itself, which is fine. The issue is that the GetObject and PutObject actions are only granted for objects, but the job might need s3:PutObject for the specific prefix. Actually, the policy seems correct. Re-examining: The error might be due to missing s3:GetObject on the output prefix? No, wildcard covers all prefixes. Perhaps the bucket policy denies access? But the question implies the IAM policy is missing something. Common missing permission is s3:GetBucketLocation for cross-account access, but not in this case. Another possibility: the job needs to delete temporary files? The exhibit shows no DeleteObject permission. So option C: s3:DeleteObject is likely needed for Glue cleanup. Option A is for listing, already present. Option B is not needed for writing. Option D is for multipart upload, but not required for small files.
What should I do if I get this DEA-C01 question wrong?
Review ACL processing order, placement rules (standard near destination, extended near source), and inbound vs outbound direction. Study wildcard masks and implicit deny. Then practise related DEA-C01 ACL questions on filtering logic and placement.
What is the key concept behind this question?
Standard ACLs match source addresses.
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