Question 900 of 1,031

Describe Azure architecture and services →hardMultiple ChoiceObjective-mapped

Quick Answer

The answer is Transparent Data Encryption (TDE) with customer-managed keys. This is the correct choice because TDE automatically encrypts the database at rest using a Database Encryption Key (DEK), and when you store the key protector in Azure Key Vault as a customer-managed key, you retain full control over key rotation. Crucially, Azure SQL Database handles re-encryption of the DEK with the new key version transparently in the background, meaning the database remains fully online and accessible with zero downtime or performance degradation during the rotation process. On the AZ-900 exam, this scenario tests your understanding of data encryption responsibilities and the shared responsibility model—specifically that customer-managed keys give you control while Azure manages the operational overhead. A common trap is confusing this with Always Encrypted, which protects data in transit and in use, not at rest. Memory tip: TDE for “Transparent” rotation—the key change happens behind the scenes, so you never see the database go offline.

AZ-900 Describe Azure architecture and services Practice Question

This AZ-900 practice question tests your understanding of describe azure architecture and services. 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 wants to encrypt data at rest in Azure SQL Database using customer-managed keys stored in Azure Key Vault. They also need to be able to rotate the keys without downtime. Which feature should they use?

Question 1hardmultiple choice

Full question →

A
Transparent Data Encryption with customer-managed keys
Correct. TDE with customer-managed keys in Azure Key Vault provides full control over encryption keys and supports online key rotation without impacting availability.
B
Always Encrypted
Why wrong: Incorrect. Always Encrypted encrypts sensitive data on the client side and never exposes plaintext to the database engine, but it is not for at-rest encryption of the entire database and does not support TDE key rotation.
C
Dynamic Data Masking
Why wrong: Incorrect. Dynamic data masking obfuscates data in query results to unauthorized users, but does not provide encryption at rest or key management.
D
Row-level security
Why wrong: Incorrect. Row-level security restricts access to rows based on user context, not encryption at rest.

Full breakdown with real-world context →

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

✓

Transparent Data Encryption with customer-managed keys

Transparent Data Encryption (TDE) with customer-managed keys in Azure Key Vault allows you to encrypt the database at rest using your own keys, which you can rotate without downtime because Azure SQL Database handles the re-encryption of the database encryption key (DEK) transparently in the background, without requiring database offline or performance impact.

Key principle: Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.

Answer analysis

Option-by-option breakdown

For each option: why learners choose it and why it is or isn't the right answer here.

✓
Transparent Data Encryption with customer-managed keys
Why this is correct
Correct. TDE with customer-managed keys in Azure Key Vault provides full control over encryption keys and supports online key rotation without impacting availability.
Related concept
Read the scenario before looking for a memorised answer.
✗
Always Encrypted
Why it's wrong here
Incorrect. Always Encrypted encrypts sensitive data on the client side and never exposes plaintext to the database engine, but it is not for at-rest encryption of the entire database and does not support TDE key rotation.
✗
Dynamic Data Masking
Why it's wrong here
Incorrect. Dynamic data masking obfuscates data in query results to unauthorized users, but does not provide encryption at rest or key management.
✗
Row-level security
Why it's wrong here
Incorrect. Row-level security restricts access to rows based on user context, not encryption at rest.

Common exam traps

Common exam trap: answer the scenario, not the keyword

The trap here is that candidates confuse Always Encrypted (client-side column encryption) with TDE (server-side at-rest encryption), or assume Dynamic Data Masking provides encryption, when neither meets the requirement for at-rest encryption with customer-managed key rotation.

Detailed technical explanation

How to think about this question

TDE with customer-managed keys uses a hierarchical key model: a database encryption key (DEK) is encrypted by a key encryption key (KEK) stored in Azure Key Vault. When rotating the KEK, Azure SQL Database automatically re-encrypts the DEK with the new KEK using the ALTER DATABASE SCOPED CONFIGURATION SET TDE_KEY_ROTATION = ON command, ensuring zero downtime. In a real-world scenario, this is critical for compliance with regulations like PCI DSS or GDPR that require periodic key rotation without service interruption.

KKey Concepts to Remember

Read the scenario before looking for a memorised answer.
Find the constraint that changes the correct option.
Eliminate answers that are true in general but not in this case.

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

Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.

Real-world example

How this comes up in practice

A cloud solutions architect for a retail company is evaluating services for a new workload. The correct answer here reflects best practice for the specific scenario described — not a general cloud recommendation. Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option. Cloud exam questions reward reading the constraint carefully: the same technology can be right or wrong depending on the use case.

What to study next

Got this wrong? Here's your next step.

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

Questions learners often ask

What does this AZ-900 question test?

Describe Azure architecture and services — This question tests Describe Azure architecture and services — Read the scenario before looking for a memorised answer..

What is the correct answer to this question?

The correct answer is: Transparent Data Encryption with customer-managed keys — Transparent Data Encryption (TDE) with customer-managed keys in Azure Key Vault allows you to encrypt the database at rest using your own keys, which you can rotate without downtime because Azure SQL Database handles the re-encryption of the database encryption key (DEK) transparently in the background, without requiring database offline or performance impact.

What should I do if I get this AZ-900 question wrong?

Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.

What is the key concept behind this question?

Read the scenario before looking for a memorised answer.

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