CAS-004 Security Architecture Practice Question
A company is migrating critical workloads to AWS and must secure data at rest. They need to maintain control over the encryption keys. Which service should they use to meet this requirement?
⚠ Common exam trap
CAS-005 often tests the difference between key management services, and candidates may confuse CloudHSM with KMS or Secrets Manager, overlooking the need for dedicated hardware control.
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
✓
AWS CloudHSM
AWS CloudHSM provides dedicated hardware security modules that give the customer full control over encryption keys, including key generation, storage, and management. It meets the requirement of maintaining control over keys for data at rest because the keys are stored in tamper-resistant hardware and are not accessible to AWS. Other services like Secrets Manager and ACM manage keys but do not offer the same level of customer-controlled key custody.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
AWS Secrets Manager
Why it's wrong here
Secrets Manager stores and rotates credentials, API keys and database passwords, not the customer-managed keys encrypting data at rest. It tempts because it is a security service holding sensitive values, but key custody for at-rest encryption belongs to AWS KMS with customer-managed keys.
- ✗
AWS Certificate Manager (ACM)
Why it's wrong here
ACM provisions and renews TLS certificates for data in transit; it does not manage the keys encrypting stored data. It tempts because it is a key-and-certificate service, but its scope is public/private certificate issuance and HTTPS termination, not customer-controlled at-rest encryption keys.
- ✓
AWS CloudHSM
Why this is correct
CloudHSM provides dedicated, single-tenant hardware security modules where the organisation retains sole control of key material; AWS cannot access the keys. This satisfies the stem's requirement to maintain control over encryption keys for data at rest, unlike KMS, where AWS manages the underlying key infrastructure.
- ✗
AWS Shield
Why it's wrong here
AWS Shield provides DDoS protection for network and application layers, not encryption key custody. It tempts because it is a security service guarding workloads, but it addresses availability under attack rather than controlling the keys that encrypt data at rest.
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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About these practice questions
This CAS-005 question is part of Courseiva's 973-question bank — original exam-style content with full explanations and wrong-answer analysis, never real exam questions or exam dumps. Learn why practice questions differ from exam dumps →
JA
Written and reviewed by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
Last reviewed September 2026 · checked against the official CompTIA exam blueprint
This CAS-005 practice question is part of Courseiva's free CompTIA 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 CAS-005 exam.