easyMultiple Choice
CISA Practice Question: A small business wants to protect customer data…
A small business wants to protect customer data collected through its e-commerce website. Which control is most appropriate for protecting the data at rest and in transit?
⚠ Common exam trap
It's easy for candidates to confuse preventive controls like firewalls or IDS with data protection mechanisms, failing to recognize that encryption is the only direct safeguard for data confidentiality both at rest and in transit.
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
✓
Use encryption for data at rest and in transit.
Encryption is the only control that directly protects the confidentiality and integrity of data both at rest (e.g., AES-256 for database files) and in transit (e.g., TLS 1.3 for HTTPS). It renders data unreadable without the proper decryption key, ensuring that even if storage media or network traffic is intercepted, the customer data remains secure.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
Implement a network firewall to block unauthorized access.
Why it's wrong here
A network firewall filters traffic at the perimeter and provides no encryption of stored customer records or data in transit, so it fails the at-rest and in-transit requirement. It would be correct for controlling inbound and outbound connections, not for protecting the data itself.
- ✗
Perform regular backups of the database to ensure data availability.
Why it's wrong here
Backups restore availability after loss; they neither encrypt data at rest nor protect it in transit, so confidentiality remains exposed. The tempting fit is resilience: for a ransomware or corruption scenario where recovery point objectives matter, scheduled database backups are the right control.
- ✗
Deploy an intrusion detection system (IDS) to monitor for threats.
Why it's wrong here
An IDS passively monitors network traffic for malicious signatures; it cannot encrypt stored records or secure data moving between browser and server. It is tempting because it addresses threats, and would be correct where the requirement is detecting intrusions rather than protecting data confidentiality.
- ✓
Use encryption for data at rest and in transit.
Why this is correct
Encryption applies cryptographic protection to customer data both at rest and in transit, directly meeting the stem's dual requirement. At rest, it renders stored records unreadable; in transit, TLS or similar protects data moving between the browser and web server.
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
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JA
Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
This CISA practice question is part of Courseiva's free ISACA 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 CISA exam.