The answer is that the service principal in the bucket policy is incorrect; it must be 'cloudtrail.amazonaws.com' instead of 'delivery.logs.amazonaws.com'. CloudTrail requires this specific principal to assume the necessary permissions to write log files to the S3 bucket, and using the wrong principal breaks the trust relationship, causing CloudTrail to fail silently when delivering logs. On the AWS Certified DevOps Engineer Professional DOP-C02 exam, this scenario tests your understanding of how CloudTrail integrates with S3 bucket policies, often appearing as a common trap where candidates confuse the delivery service principal with the CloudTrail service principal. A key memory tip is to remember that CloudTrail itself, not a separate delivery service, must be the explicit principal in the policy—think "CloudTrail writes, delivery just delivers."
DOP-C02 Incident and Event Response Practice Question
This DOP-C02 practice question tests your understanding of incident and event response. 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.
Network Topology
A company configures AWS CloudTrail to deliver logs to S3 bucket 'my-app-logs'. However, no log files appear. The DevOps engineer runs the above command and sees the bucket policy. What is the issue?
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
The service principal in the bucket policy is incorrect; it should be 'cloudtrail.amazonaws.com'.
Option D is correct because CloudTrail requires the S3 bucket policy to grant the service principal 'cloudtrail.amazonaws.com', not 'delivery.logs.amazonaws.com'. Option A is wrong because the policy allows PutObject. Option B is wrong because CloudTrail can deliver to buckets with ACL settings as long as the policy is correct. Option C is wrong because the bucket exists and the policy is present.
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.
✗
The bucket policy requires bucket-owner-full-control ACL, but CloudTrail does not support ACLs.
The bucket policy does not allow the s3:PutObject action.
Why it's wrong here
The policy does allow PutObject.
✓
The service principal in the bucket policy is incorrect; it should be 'cloudtrail.amazonaws.com'.
Why this is correct
CloudTrail requires its own service principal.
Related concept
Standard ACLs match source addresses.
✗
The bucket does not exist; the policy retrieval failed silently.
Why it's wrong here
The policy was retrieved successfully, so the bucket exists.
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 DOP-C02 ACL questions on filtering logic and placement.
Incident and Event Response — This question tests Incident and Event Response — Standard ACLs match source addresses..
What is the correct answer to this question?
The correct answer is: The service principal in the bucket policy is incorrect; it should be 'cloudtrail.amazonaws.com'. — Option D is correct because CloudTrail requires the S3 bucket policy to grant the service principal 'cloudtrail.amazonaws.com', not 'delivery.logs.amazonaws.com'. Option A is wrong because the policy allows PutObject. Option B is wrong because CloudTrail can deliver to buckets with ACL settings as long as the policy is correct. Option C is wrong because the bucket exists and the policy is present.
What should I do if I get this DOP-C02 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 DOP-C02 ACL questions on filtering logic and placement.
What is the key concept behind this question?
Standard ACLs match source addresses.
About these practice questions
Courseiva creates original exam-style practice questions with explanations and wrong-answer analysis. It does not publish real exam questions, exam dumps, or protected exam content. Learn why practice questions differ from exam dumps →
These questions test the same concept from different angles. Work through them to make sure you can recognise it however the exam phrases it.
Variation 1. Drag and drop the steps to troubleshoot an AWS CloudTrail that is not logging API calls.
medium
Why : First verify CloudTrail is enabled, then check bucket policy, then check integrity, then check IAM role, then test.
Last reviewed: Jun 20, 2026
Question Discussion
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This DOP-C02 practice question is part of Courseiva's free Amazon Web Services certification practice question bank. Courseiva provides original exam-style practice questions with explanations, topic-based practice, mock exams, readiness tracking, and study analytics to help learners prepare for the DOP-C02 exam.
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