Question 1,133 of 1,748
Threat Detection and Incident ResponsehardMultiple ChoiceObjective-mapped

Why CloudTrail Logs Are Missing from a Member Account: S3 Bucket Policy Size Limit

This SCS-C02 practice question tests your understanding of threat detection and incident response. This is a configuration task: choose the command set that satisfies every stated requirement. Small differences — like 'secret' vs 'password' or 'transport input ssh' vs 'all' — change whether the answer is correct. A key principle to apply: service Control Policy (SCP). 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 financial services company uses AWS Organizations with over 100 accounts. The security team uses AWS CloudTrail to log all API calls to a central S3 bucket in the security account. The bucket policy enables cross-account log delivery from all member accounts. The team notices that some API calls from a specific member account are not appearing in the central bucket. The CloudTrail trail in that member account is configured to deliver logs to the central bucket. The IAM role used by CloudTrail in the member account has permissions to write to the central bucket. The security team has verified that the bucket policy allows the member account to write. What is the MOST likely cause of the missing logs?

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 choices

Why each option matters

Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.

Correct answer & explanation

A service control policy (SCP) is denying the CloudTrail service in the member account from writing to the central bucket.

A service control policy (SCP) can explicitly deny the CloudTrail service (or any service) from performing actions in a member account. Even if the IAM role and bucket policy allow writing, an SCP that denies the `cloudtrail:PutEventSelectors` or `cloudtrail:CreateTrail` actions, or denies access to the S3 bucket, would prevent CloudTrail from delivering logs to the central bucket. Since SCPs can be applied at the account level, this explains why only one specific member account is affected.

Key principle: Service Control Policy (SCP)

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 S3 bucket policy in the central bucket exceeds the size limit, causing write failures for some accounts.

    Why it's wrong here

    If the bucket policy exceeded the 20,480-character limit, AWS would reject the entire policy, causing all writes to fail, not just for one account. This is inconsistent with the scenario where only one account is missing logs.

  • The CloudTrail trail in the member account is not a multi-region trail.

    Why it's wrong here

    If the trail were not multi-region, CloudTrail would only log API calls from the single region where the trail is created. This could cause missing logs from other regions, but the scenario describes missing logs from one account, not one region, and the trail is configured to deliver logs to the central bucket, implying it is working for other regions.

  • The member account has not enabled CloudTrail logging for the specific region.

    Why it's wrong here

    If CloudTrail logging were not enabled for the specific region, no logs from that region would appear. However, the trail is configured and delivering logs (otherwise all logs would be missing), so this is unlikely the cause for missing 'some' API calls.

  • A service control policy (SCP) is denying the CloudTrail service in the member account from writing to the central bucket.

    Why this is correct

    A service control policy (SCP) can deny CloudTrail from writing to the central bucket for a specific account. This is a common cause of missing logs for a single account in an AWS Organizations setup, and it aligns with the scenario.

    Clue confirmation

    The clue word "most likely" in the question point toward this answer.

    Related concept

    Service Control Policy (SCP)

Common exam traps

Common exam trap: answer the scenario, not the keyword

Candidates often overlook service control policies (SCPs) as a cause for missing CloudTrail logs, focusing instead on IAM permissions and bucket policies. SCPs can override permissions at the account level, affecting only specific accounts.

Trap categories for this question

  • Scenario analysis trap

    If the bucket policy exceeded the 20,480-character limit, AWS would reject the entire policy, causing all writes to fail, not just for one account. This is inconsistent with the scenario where only one account is missing logs.

Detailed technical explanation

How to think about this question

AWS S3 bucket policies are subject to a 20,480 character limit, and when exceeded, AWS may silently reject updates or cause partial enforcement, leading to intermittent write failures for specific principals. In large AWS Organizations setups, administrators often add individual account ARNs or organization IDs to the bucket policy, which can quickly consume the character limit. A real-world scenario involves using AWS CloudTrail with organization trails, which automatically aggregate logs from all accounts without needing per-account bucket policy entries, avoiding this limit issue.

KKey Concepts to Remember

  • Service Control Policy (SCP)
  • AWS CloudTrail
  • S3 Bucket Policy

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

Service Control Policy (SCP)

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.

Quick reference

AWS S3 Storage Class Comparison

Storage ClassMin DurationRetrievalUse Case
S3 StandardNoneImmediateFrequently accessed data
S3 Standard-IA30 daysImmediateInfrequent access, rapid retrieval
S3 One Zone-IA30 daysImmediateNon-critical infrequent data
S3 Intelligent-TieringNoneImmediate–hoursUnknown or changing access patterns
S3 Glacier Instant90 daysMillisecondsArchive with instant retrieval
S3 Glacier Flexible90 daysMinutes–hoursArchive, flexible retrieval
S3 Glacier Deep Archive180 daysHoursLong-term compliance archive

What to study next

Got this wrong? Here's your next step.

Review service Control Policy (SCP), then practise related SCS-C02 questions on the same topic to reinforce the concept.

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FAQ

Questions learners often ask

What does this SCS-C02 question test?

Threat Detection and Incident Response — This question tests Threat Detection and Incident Response — Service Control Policy (SCP).

What is the correct answer to this question?

The correct answer is: A service control policy (SCP) is denying the CloudTrail service in the member account from writing to the central bucket. — A service control policy (SCP) can explicitly deny the CloudTrail service (or any service) from performing actions in a member account. Even if the IAM role and bucket policy allow writing, an SCP that denies the `cloudtrail:PutEventSelectors` or `cloudtrail:CreateTrail` actions, or denies access to the S3 bucket, would prevent CloudTrail from delivering logs to the central bucket. Since SCPs can be applied at the account level, this explains why only one specific member account is affected.

What should I do if I get this SCS-C02 question wrong?

Review service Control Policy (SCP), then practise related SCS-C02 questions on the same topic to reinforce the concept.

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?

Service Control Policy (SCP)

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Last reviewed: Jun 24, 2026

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This SCS-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 SCS-C02 exam.