The correct configuration is Transparent Data Encryption (TDE) with Azure Key Vault, as this is the only Azure SQL Database feature that encrypts the entire database at rest using customer-managed keys (CMK) while remaining completely transparent to applications. TDE performs real-time I/O encryption and decryption of the data and log files, and when paired with a CMK stored in a key vault that has soft-delete and purge protection enabled, it meets the financial services requirement for full control over encryption keys without any application code changes. On the Microsoft Cybersecurity Architect exam, this question tests your ability to distinguish between data-at-rest encryption solutions—Always Encrypted is a common trap because it encrypts at the column level and requires client-side driver changes, whereas TDE is the correct choice for transparent, database-wide encryption. A helpful memory tip is to think of TDE as the “full-disk encryption” for Azure SQL, while Always Encrypted is more like “encrypting individual files” that the application must unlock.
SC-100 Design security solutions for infrastructure Practice Question
This SC-100 practice question tests your understanding of design security solutions for infrastructure. This is a configuration task: choose the command set that satisfies every stated requirement. Small differences — like 'secret' vs 'password' or 'transport input ssh' vs 'all' — change whether the answer is correct. 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 financial services company is designing a secure infrastructure for their Azure SQL Database. They need to encrypt data at rest using customer-managed keys (CMK) stored in a key vault with soft-delete and purge protection enabled. The encryption must be transparent to applications. What should they configure?
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 (TDE) with Azure Key Vault
Azure SQL Database supports Transparent Data Encryption (TDE) with CMK in Azure Key Vault. Always Encrypted is for column-level encryption. Dynamic Data Masking is for masking, not encryption. Azure Information Protection is for classification.
Key principle: Count usable hosts — not total addresses — and remember that the network and broadcast addresses are not available to hosts in standard IPv4 subnets.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
✗
Azure Information Protection
Why it's wrong here
Incorrect: AIP is for classification and labeling, not database encryption.
✗
Dynamic Data Masking
Why it's wrong here
Incorrect: Dynamic Data Masking does not encrypt data; it masks it for users.
✗
Always Encrypted
Why it's wrong here
Incorrect: Always Encrypted is column-level and requires application changes.
✓
Transparent Data Encryption (TDE) with Azure Key Vault
Why this is correct
Correct: TDE with CMK provides transparent encryption at rest.
Common exam trap: usable hosts are not the same as total addresses
Subnetting questions often tempt you into counting all addresses. In normal IPv4 subnets, the network and broadcast addresses are not usable host addresses.
Detailed technical explanation
How to think about this question
Subnetting questions test whether you can identify the network, broadcast address, usable range, mask and correct subnet. Slow down enough to calculate the block size correctly.
KKey Concepts to Remember
CIDR notation defines the prefix length.
Block size helps identify subnet boundaries.
Network and broadcast addresses are not usable hosts in normal IPv4 subnets.
The required host count determines the smallest suitable subnet.
TExam Day Tips
→Write the block size before choosing the subnet.
→Check whether the question asks for hosts, subnets or a specific address range.
→Do not confuse /24, /25, /26 and /27 host counts.
Key takeaway
Count usable hosts — not total addresses — and remember that the network and broadcast addresses are not available to hosts in standard IPv4 subnets.
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. Count usable hosts — not total addresses — and remember that the network and broadcast addresses are not available to hosts in standard IPv4 subnets. Cloud exam questions reward reading the constraint carefully: the same technology can be right or wrong depending on the use case.
Related glossary terms
Concepts from this question explained
These glossary pages explain the core terms tested in this SC-100 question in full detail.
Review block sizes, usable host formulas (2^n − 2), and how to find network and broadcast addresses for /24 through /30. Then practise related SC-100 subnetting questions on CIDR, address ranges, and subnet selection.
Design security solutions for infrastructure — This question tests Design security solutions for infrastructure — CIDR notation defines the prefix length..
What is the correct answer to this question?
The correct answer is: Transparent Data Encryption (TDE) with Azure Key Vault — Azure SQL Database supports Transparent Data Encryption (TDE) with CMK in Azure Key Vault. Always Encrypted is for column-level encryption. Dynamic Data Masking is for masking, not encryption. Azure Information Protection is for classification.
What should I do if I get this SC-100 question wrong?
Review block sizes, usable host formulas (2^n − 2), and how to find network and broadcast addresses for /24 through /30. Then practise related SC-100 subnetting questions on CIDR, address ranges, and subnet selection.
What is the key concept behind this question?
CIDR notation defines the prefix length.
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