PAS-C01 Technology Practice Question
A company uses AWS Organizations with multiple accounts. The security team wants to enforce that all S3 buckets in the organization are encrypted with SSE-KMS using a specific KMS key. What is the MOST effective way to enforce this policy?
⚠ Common exam trap
Many exam-takers choose detective controls like AWS Config (Option A) or account-level IAM policies (Option B) because they are familiar with them, failing to recognize that only SCPs provide preventive, organization-wide enforcement that cannot be bypassed by account administrators.
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
✓
Attach a service control policy (SCP) to the root organizational unit that denies s3:PutBucketEncryption unless the encryption settings include the specific KMS key.
Service control policies (SCPs) are the most effective way to enforce encryption requirements across all accounts in an AWS Organization because they act as a centralized guardrail that cannot be overridden by account administrators. By attaching an SCP to the root organizational unit that denies s3:PutBucketEncryption unless the request includes the specific KMS key ARN, the security team ensures that no bucket can be created or modified without the mandated encryption, regardless of IAM permissions within individual accounts.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
Use AWS Config rules to detect noncompliant buckets and send notifications.
Why it's wrong here
This is detective, not preventive; buckets can still be created without encryption.
- ✗
Create an IAM policy in each account that denies s3:PutBucketEncryption unless the correct KMS key is specified.
Why it's wrong here
IAM policies are per-account and do not prevent root user actions or actions by other services.
- ✓
Attach a service control policy (SCP) to the root organizational unit that denies s3:PutBucketEncryption unless the encryption settings include the specific KMS key.
Why this is correct
SCPs apply to all accounts in the OU and can prevent noncompliant bucket creation, including by the root user.
- ✗
Use AWS CloudFormation StackSets to deploy a template that creates all buckets with the required encryption.
Why it's wrong here
This does not prevent users from creating buckets outside of CloudFormation.
Quick reference
AWS S3 Storage Class Comparison
| Storage Class | Min Duration | Retrieval | Use Case |
|---|---|---|---|
| S3 Standard | None | Immediate | Frequently accessed data |
| S3 Standard-IA | 30 days | Immediate | Infrequent access, rapid retrieval |
| S3 One Zone-IA | 30 days | Immediate | Non-critical infrequent data |
| S3 Intelligent-Tiering | None | Immediate–hours | Unknown or changing access patterns |
| S3 Glacier Instant | 90 days | Milliseconds | Archive with instant retrieval |
| S3 Glacier Flexible | 90 days | Minutes–hours | Archive, flexible retrieval |
| S3 Glacier Deep Archive | 180 days | Hours | Long-term compliance archive |
Go deeper
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JA
Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
This PAS-C01 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 PAS-C01 exam.