CAS-004 Security Architecture Practice Question
A financial services company is designing a secure multi-tenant SaaS application hosted on AWS. The security architect must ensure that each tenant's data is isolated and that encryption keys are unique per tenant, while allowing the company to manage keys centrally. Which AWS service should the architect use to meet these requirements?
⚠ Common exam trap
Watch out — candidates often confuse data-in-transit certificate management or secret storage with encryption key management for data at rest, which requires a dedicated key management service such as KMS.
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 Key Management Service (KMS) with customer managed keys (CMKs) and encryption context per tenant.
AWS KMS with customer managed keys allows the architect to create a unique key for each tenant and use encryption context to enforce that only the intended tenant can decrypt its data. This centralizes key management while providing cryptographic isolation, satisfying both the per-tenant key requirement and the need for central administration.
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 Certificate Manager (ACM) with a wildcard certificate per tenant.
Why it's wrong here
ACM manages TLS certificates for encrypting data in transit, not encryption keys for data at rest. Wildcard certificates per tenant do not provide cryptographic isolation of tenant data, and ACM does not offer the key management and policy controls needed for per-tenant encryption keys.
- ✗
AWS CloudHSM with a single cluster shared across all tenants.
Why it's wrong here
A single CloudHSM cluster shared across tenants does not provide unique keys per tenant unless the application manages key separation manually. CloudHSM offers dedicated hardware but lacks the integrated per-tenant key management and centralized policy controls that KMS provides, increasing operational complexity.
- ✓
AWS Key Management Service (KMS) with customer managed keys (CMKs) and encryption context per tenant.
Why this is correct
AWS KMS customer managed keys allow the company to create and manage unique keys per tenant, and encryption context can enforce tenant-specific authorization. This provides centralized key management with per-tenant cryptographic isolation, meeting the requirement for unique encryption keys and central control.
- ✗
AWS Secrets Manager with automatic rotation for each tenant's database credentials.
Why it's wrong here
Secrets Manager is designed for storing and rotating secrets such as database credentials, not for managing encryption keys used to protect tenant data. It does not provide cryptographic key material or encryption context controls, so it cannot ensure unique encryption keys per tenant for data at rest.
Go deeper
Related to this question
About these practice questions
One of 973 original CAS-005 practice questions on Courseiva, each with a full explanation and wrong-answer analysis — not exam dumps or protected exam content. 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.