Always Encrypted with the column master key stored in Azure Key Vault is the correct choice because it provides true column-level encryption for sensitive data in Azure SQL Database, ensuring that patient SSNs are encrypted both at rest and in transit and that only authorized client applications with access to the key can decrypt them. This technology works by keeping the encryption keys client-side, so even database administrators or cloud operators cannot view the plaintext values, which directly addresses the requirement for protecting sensitive columns from unauthorized access. On the Microsoft Azure Database Administrator Associate DP-300 exam, this scenario tests your understanding of how Always Encrypted differs from Transparent Data Encryption (TDE), which only encrypts data at rest and does not prevent privileged users from seeing the data. A common trap is choosing TDE or dynamic data masking, but remember that Always Encrypted is the only option that guarantees the database system itself never sees the plaintext. Memory tip: think "Always Encrypted = Always hidden from the server."
DP-300 Implement a secure environment Practice Question
This DP-300 practice question tests your understanding of implement a secure environment. 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.
You are the database administrator for a healthcare organization that uses Azure SQL Database. You need to implement column-level encryption for a column containing patient Social Security numbers (SSNs). The SSNs must be encrypted at rest and in transit, and only authorized client applications should be able to decrypt them. Which technology should you use?
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Always Encrypted with column master key stored in Azure Key Vault.
Always Encrypted is the correct choice because it ensures that sensitive data, such as SSNs, is encrypted both at rest and in transit, and the encryption keys are stored client-side (e.g., in Azure Key Vault). This design ensures that only authorized client applications with access to the column master key can decrypt the data, preventing even database administrators or cloud operators from viewing the plaintext values.
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.
✗
Row-level security (RLS) to restrict access based on user role.
Why it's wrong here
RLS controls access to rows, not encryption of individual columns.
✗
Dynamic data masking (DDM) to mask SSNs for unauthorized users.
Why it's wrong here
DDM only obfuscates data in query results; it does not encrypt the underlying data.
✗
Transparent Data Encryption (TDE) with customer-managed keys.
Why it's wrong here
TDE encrypts data at rest but does not protect data in transit or control client-side decryption.
✓
Always Encrypted with column master key stored in Azure Key Vault.
Why this is correct
Always Encrypted encrypts column data at rest and in transit, and only clients with access to the column master key can decrypt.
Related concept
Read the scenario before looking for a memorised answer.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates often confuse Transparent Data Encryption (TDE) with column-level encryption, mistakenly thinking TDE protects data from all unauthorized access, when in fact TDE only encrypts data at rest and does not prevent authorized database users from reading sensitive columns in plaintext.
Detailed technical explanation
How to think about this question
Always Encrypted uses two-tier key hierarchy: a column encryption key (CEK) that encrypts the column data, and a column master key (CMK) that encrypts the CEK. The CMK is stored in Azure Key Vault and never exposed to the database engine, ensuring that only the client application with access to the CMK can decrypt the CEK and thus the SSNs. This architecture guarantees that the encryption keys are never transmitted to the server, providing true separation of duties and protecting data even from high-privilege users like sysadmins.
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 company's IT admin needs to give a contractor read-only access to production logs without sharing account credentials. Using role-based access control (RBAC) and temporary scoped permissions — not a permanent shared password — is the correct pattern. Questions like this test whether you can apply least-privilege access across cloud identity services.
Related glossary terms
Concepts from this question explained
These glossary pages explain the core terms tested in this DP-300 question in full detail.
Implement a secure environment — This question tests Implement a secure environment — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: Always Encrypted with column master key stored in Azure Key Vault. — Always Encrypted is the correct choice because it ensures that sensitive data, such as SSNs, is encrypted both at rest and in transit, and the encryption keys are stored client-side (e.g., in Azure Key Vault). This design ensures that only authorized client applications with access to the column master key can decrypt the data, preventing even database administrators or cloud operators from viewing the plaintext values.
What should I do if I get this DP-300 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.
About these practice questions
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These questions test the same concept from different angles. Work through them to make sure you can recognise it however the exam phrases it.
Variation 1. You are the database administrator for a healthcare organization that uses Azure SQL Database. You need to implement column-level encryption for sensitive patient data (e.g., Social Security numbers) using Always Encrypted. The application connecting to the database is a .NET application running on Azure Virtual Machines. The application should be able to perform parameterized queries on encrypted columns without revealing the plaintext to the database. Which configuration is essential for this setup?
hard
✓ A.Use Always Encrypted with secure enclaves and configure the enclave attestation URL.
B.Store the column master key in Azure Key Vault and configure the application to retrieve it.
C.Implement dynamic data masking on the columns containing Social Security numbers.
D.Enable Transparent Data Encryption (TDE) on the database.
Why A: Option D is correct because Always Encrypted with secure enclaves (using Intel SGX) allows rich computations on encrypted data within the enclave. Option A is incorrect because column master key stored in Azure Key Vault is standard, but the enclave is needed for computations. Option B is incorrect because Transparent Data Encryption encrypts data at rest, not in use. Option C is incorrect because dynamic data masking only obfuscates data from certain users, but the database can still see the plaintext.
Last reviewed: Jun 24, 2026
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