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ISC2 CC Practice Question: A company's security policy requires that all…
A company's security policy requires that all data at rest be encrypted. Which of the following is the BEST approach to ensure compliance while maintaining performance?
⚠ Common exam trap
ISC2 often tests the distinction between 'data at rest' and 'data in transit' encryption, and the trap here is that candidates may choose database or file-level encryption because they think it is more targeted, but they overlook the policy's explicit 'all data at rest' requirement, which only full disk encryption satisfies comprehensively.
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
✓
Deploy full disk encryption on all endpoints and servers.
Full disk encryption (FDE) encrypts the entire storage volume, including the operating system, applications, and all data at rest, ensuring compliance with a policy requiring all data at rest to be encrypted. FDE operates at the block level, typically using AES-256, with minimal performance overhead because encryption and decryption are handled by the disk controller or CPU with hardware acceleration (e.g., AES-NI), making it the best approach for maintaining performance while meeting the broad requirement.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✓
Deploy full disk encryption on all endpoints and servers.
Why this is correct
Full disk encryption satisfies the data-at-rest requirement by encrypting the entire volume, including temporary and swap files, so no plaintext persists on lost or stolen media. Encryption occurs at the storage layer via hardware or OS drivers, adding negligible latency compared with application-level or database encryption, thus preserving performance.
- ✗
Use database encryption to protect sensitive data.
Why it's wrong here
Database encryption protects only data inside the database, leaving other data at rest (object storage, backups, volumes) unencrypted, so the policy is not met. It is tempting because column or TDE encryption targets sensitive fields with minimal overhead, and would be right when only specific database columns need protection.
- ✗
Apply network encryption using TLS for all data transfers.
Why it's wrong here
TLS protects data in transit, not at rest, so it fails the policy requirement regardless of performance. It is tempting because TLS is the standard answer for encryption questions, and it is correct when the requirement is protecting data moving between systems.
- ✗
Implement file-level encryption for sensitive files only.
Why it's wrong here
File-level encryption covers only selected files, leaving other data at rest unencrypted and so non-compliant. It is tempting because it limits performance overhead, and it is correct when only a defined subset of data requires protection.
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 |
Go deeper
Related to this question
Learn chapter
Security Governance and Compliance
Key term
General Data Protection Regulation
A European Union law that gives individuals control over their personal data and sets strict rules for how organizations collect, store, and process that data.
Key term
Encryption
Encryption is the process of converting readable data into a secret code to prevent unauthorized access.
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JA
Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
This CC practice question is part of Courseiva's free ISC2 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 CC exam.