Quick Answer
The answer is Azure Blob Storage and Azure SQL Database, as both services support customer-managed keys (CMK) for encryption at rest. This is correct because CMK allows you to bring your own encryption keys (BYOK) via Azure Key Vault, giving your organization full control over key lifecycle operations such as rotation, revocation, and access auditing—critical for sensitive customer data. On the Microsoft Azure Solutions Architect Expert AZ-305 exam, this concept tests your understanding of data encryption responsibilities and the distinction between platform-managed keys and customer-managed keys. A common trap is assuming only Blob Storage supports CMK, but Azure SQL Database also offers Transparent Data Encryption (TDE) with CMK through Azure Key Vault. For a quick memory tip, remember the phrase “Blob and SQL, keys you control”—if the scenario demands full encryption control for compliance or regulatory reasons, both services are the correct pair.
This AZ-305 practice question tests your understanding of design data storage solutions. Match the stated requirement to the specific cloud service, access model, or configuration option — many options are valid in isolation but not for this scenario. 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 needs to store sensitive customer data that must be encrypted at rest. Which TWO Azure storage services support customer-managed keys (CMK) for encryption?
Azure Files
Why wrong: Supports CMK only for premium shares.
Azure SQL Database
Supports CMK with Azure Key Vault.
Azure Cache for Redis
Why wrong: Does not support CMK.
Azure Blob Storage
Supports CMK with Azure Key Vault.
Azure Cosmos DB
Why wrong: Supports CMK at account level, but the question asks for storage services.
Answer choices
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
Azure SQL Database
Azure SQL Database and Azure Blob Storage both support customer-managed keys (CMK) via Azure Key Vault, allowing you to bring your own encryption keys (BYOK) for data at rest. This meets the requirement for sensitive customer data where the organization needs full control over encryption keys, including key rotation and revocation.
Key principle: Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Answer analysis
For each option: why learners choose it and why it is or isn't the right answer here.
Azure Files
Why it's wrong here
Supports CMK only for premium shares.
Azure SQL Database
Why this is correct
Supports CMK with Azure Key Vault.
Related concept
Read the scenario before looking for a memorised answer.
Azure Cache for Redis
Why it's wrong here
Does not support CMK.
Azure Blob Storage
Why this is correct
Supports CMK with Azure Key Vault.
Related concept
Read the scenario before looking for a memorised answer.
Azure Cosmos DB
Why it's wrong here
Supports CMK at account level, but the question asks for storage services.
Common exam traps
The trap here is that candidates often confuse services that support CMK with those that only support Microsoft-managed keys, and they may incorrectly select Azure Cosmos DB or Azure Files because they assume all Azure data services support BYOK, but only specific services like Azure SQL Database and Azure Blob Storage are explicitly tested for CMK in the AZ-305 exam.
Detailed technical explanation
Azure SQL Database uses Transparent Data Encryption (TDE) with CMK stored in Azure Key Vault, where the database encryption key (DEK) is protected by an asymmetric key (protector) that you manage. Azure Blob Storage uses envelope encryption: a content encryption key (CEK) is encrypted by a key encryption key (KEK) stored in Key Vault, allowing granular control over blob-level encryption. Both services support key rotation and revocation, which immediately disables access to encrypted data.
Key takeaway
Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Real-world example
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
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
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FAQ
Design data storage solutions — This question tests Design data storage solutions — Read the scenario before looking for a memorised answer..
The correct answer is: Azure SQL Database — Azure SQL Database and Azure Blob Storage both support customer-managed keys (CMK) via Azure Key Vault, allowing you to bring your own encryption keys (BYOK) for data at rest. This meets the requirement for sensitive customer data where the organization needs full control over encryption keys, including key rotation and revocation.
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
Read the scenario before looking for a memorised answer.
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Last reviewed: Jun 24, 2026
This AZ-305 practice question is part of Courseiva's free Microsoft 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 AZ-305 exam.
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