The answer is that the S3 bucket policy does not include a principal condition for the member account’s log delivery service. This is because the delivery.logs.amazonaws.com service principal must be explicitly granted write permissions in the bucket policy for each member account that sends flow logs; without a condition like `aws:SourceAccount` or `aws:SourceArn` scoping the principal to the member account, the policy will deny the cross-account write request. On the AWS Certified Advanced Networking Specialty ANS-C01 exam, this scenario tests your understanding of how VPC flow log delivery relies on service-linked principals rather than IAM roles, and a common trap is assuming the management account’s bucket policy alone suffices. To troubleshoot cross-account flow log delivery failure, always verify that the bucket policy includes a `Principal` element for `delivery.logs.amazonaws.com` with a condition restricting it to the member account’s ID. Memory tip: “Principal plus condition—without both, delivery’s a mission.”
ANS-C01 Network Management and Operations Practice Question
This ANS-C01 practice question tests your understanding of network management and operations. 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 company has a multi-account AWS environment using AWS Organizations. They want to centralize VPC flow logs from all accounts into a single Amazon S3 bucket in the management account. The management account S3 bucket policy allows the log delivery service to write logs. However, flow logs are failing to deliver from member accounts. What is the most likely reason?
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 S3 bucket policy does not include a principal condition for the member account's log delivery service
Option C is correct because the S3 bucket policy must explicitly allow the log delivery service principal (delivery.logs.amazonaws.com) from the member account to write objects. Option A is incorrect because flow logs can be delivered cross-account with proper permissions. Option B is incorrect because the bucket policy is evaluated, not the member account's VPC flow log role. Option D is incorrect because encryption is not the issue.
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.
✗
Flow logs cannot be delivered cross-account; they must be in the same account
Why it's wrong here
Cross-account delivery is supported with proper bucket policies.
✗
The member account's IAM role for flow logs does not have permission to write to the bucket
Why it's wrong here
Flow logs use the log delivery service, not the member account's IAM role.
✓
The S3 bucket policy does not include a principal condition for the member account's log delivery service
Why this is correct
The bucket policy must allow the log delivery service from the member account.
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 S3 bucket uses SSE-KMS encryption and the member account does not have access to the KMS key
Why it's wrong here
While KMS can cause issues, the most likely reason is the bucket policy.
Common exam traps
Common exam trap: answer the scenario, not the keyword
Many certification questions include familiar terms but test a specific constraint. Read the exact wording before choosing an answer that is generally true but wrong for this case.
Detailed technical explanation
How to think about this question
This question should be treated as a scenario, not a definition check. Identify the problem, the constraint and the best action. Then compare each option against those facts.
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.
Use explanations to understand the rule behind the answer.
TExam Day Tips
→Underline the problem statement mentally.
→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 ANS-C01 exam domain this question belongs to, then review the specific concept being tested. Practise related questions in that domain and focus on understanding why each wrong answer is tempting — not just why the correct answer is right.
Network Management and Operations — This question tests Network Management and Operations — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: The S3 bucket policy does not include a principal condition for the member account's log delivery service — Option C is correct because the S3 bucket policy must explicitly allow the log delivery service principal (delivery.logs.amazonaws.com) from the member account to write objects. Option A is incorrect because flow logs can be delivered cross-account with proper permissions. Option B is incorrect because the bucket policy is evaluated, not the member account's VPC flow log role. Option D is incorrect because encryption is not the issue.
What should I do if I get this ANS-C01 question wrong?
Identify which ANS-C01 exam domain this question belongs to, then review the specific concept being tested. Practise related questions in that domain and focus on understanding why each wrong answer is tempting — not just why the correct answer is right.
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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