- A
BitLocker Drive Encryption
Microsoft uses BitLocker to encrypt drives in datacenters.
- B
Customer-managed keys (CMK) using Azure Key Vault
Why wrong: CMK is optional, not built-in by default.
- C
Office 365 Message Encryption
Why wrong: OME encrypts email messages only.
- D
Azure Information Protection
Why wrong: AIP is for classification and labeling, not encryption at rest.
Question 397 of 985
Describe security, compliance, privacy, and trust in Microsoft 365 →easyMultiple ChoiceObjective-mapped
BitLocker Drive Encryption
This MS-900 practice question tests your understanding of describe security, compliance, privacy, and trust in microsoft 365. Read the scenario carefully and evaluate each option against the stated constraints before committing to an answer. 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.
An organization needs to ensure that all Microsoft 365 data is encrypted at rest and in transit. Which of the following is a built-in encryption mechanism in Microsoft 365?
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
✓
BitLocker Drive Encryption
BitLocker Drive Encryption is a built-in encryption mechanism in Microsoft 365 that encrypts data at rest on physical drives within Microsoft datacenters. It uses AES 256-bit encryption to protect data stored on disk volumes, ensuring that even if physical drives are removed, the data remains unreadable. Additionally, Microsoft 365 uses TLS 1.2+ for data in transit, but BitLocker specifically addresses the 'at rest' requirement as a native, default encryption layer.
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.
- ✓
BitLocker Drive Encryption
Why this is correct
Microsoft uses BitLocker to encrypt drives in datacenters.
Related concept
Read the scenario before looking for a memorised answer.
- ✗
Customer-managed keys (CMK) using Azure Key Vault
Why it's wrong here
CMK is optional, not built-in by default.
- ✗
Office 365 Message Encryption
Why it's wrong here
OME encrypts email messages only.
- ✗
Azure Information Protection
Why it's wrong here
AIP is for classification and labeling, not encryption at rest.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates confuse optional customer-managed encryption features (like CMK or OME) with the built-in, default encryption mechanisms (like BitLocker) that Microsoft automatically applies to all data at rest in its datacenters.
Detailed technical explanation
How to think about this question
BitLocker in Microsoft 365 is implemented at the volume level using the Advanced Encryption Standard (AES) with 256-bit keys, and it is enabled by default on all drives in Microsoft datacenters. This encryption is transparent to tenants and does not require any customer configuration, as it is part of the physical security controls. In a real-world scenario, if a drive is decommissioned, BitLocker ensures that the data is cryptographically erased without needing to physically destroy the drive, meeting compliance requirements like FedRAMP and SOC 2.
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.
Quick reference
Symmetric Encryption Algorithm Comparison
| Algorithm | Key Size | Block Size | Status | Notes |
|---|---|---|---|---|
| AES-128 | 128-bit | 128-bit | Current standard | NIST approved; WPA3, TLS |
| AES-256 | 256-bit | 128-bit | Current standard | Preferred for sensitive / govt data |
| 3DES | 112-bit effective | 64-bit | Deprecated (2023) | Replaced by AES |
| DES | 56-bit | 64-bit | Broken | Cracked in < 24 h; never deploy |
| ChaCha20 | 256-bit | Stream cipher | Current | TLS 1.3, WireGuard |
What to study next
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FAQ
Questions learners often ask
What does this MS-900 question test?
Describe security, compliance, privacy, and trust in Microsoft 365 — This question tests Describe security, compliance, privacy, and trust in Microsoft 365 — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: BitLocker Drive Encryption — BitLocker Drive Encryption is a built-in encryption mechanism in Microsoft 365 that encrypts data at rest on physical drives within Microsoft datacenters. It uses AES 256-bit encryption to protect data stored on disk volumes, ensuring that even if physical drives are removed, the data remains unreadable. Additionally, Microsoft 365 uses TLS 1.2+ for data in transit, but BitLocker specifically addresses the 'at rest' requirement as a native, default encryption layer.
What should I do if I get this MS-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.
About these practice questions
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Last reviewed: Jul 4, 2026
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