Quick Answer
The answer is encryption at rest and in transit, as this is the most appropriate control for protecting Confidential data. Encryption at rest secures stored data on disks, databases, or backups, while encryption in transit protects data moving across networks, ensuring that unauthorized parties cannot read it whether it is stored or being transmitted. On the CISSP exam, this scenario tests your understanding of the data lifecycle and the principle that classification labels dictate the strength and scope of cryptographic controls; a common trap is choosing only one form of encryption, such as TLS for transit or disk encryption for storage, when the label “Confidential” demands both. Remember the memory tip: “Confidential needs both locks—one on the shelf, one on the wire.”
This CISSP practice question tests your understanding of security and risk management. Compare every option against the stated constraints before choosing — the best answer satisfies all requirements, not just the most obvious one. 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 company has implemented data classification labels such as 'Public', 'Internal', 'Confidential', and 'Restricted'. Which control is most appropriate for protecting 'Confidential' data?
Data masking for all users
Why wrong: Data masking may be excessive for internal users who need access.
Encryption at rest and in transit
Encryption protects data from unauthorized access during storage and transmission.
Removing all access controls to streamline sharing
Why wrong: Removing access controls would compromise confidentiality.
Public posting on the company website
Why wrong: Public access contradicts confidentiality.
Answer choices
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
Encryption at rest and in transit
Confidential data requires encryption both at rest and in transit to prevent unauthorized disclosure.
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
For each option: why learners choose it and why it is or isn't the right answer here.
Data masking for all users
Why it's wrong here
Data masking may be excessive for internal users who need access.
Encryption at rest and in transit
Why this is correct
Encryption protects data from unauthorized access during storage and transmission.
Related concept
CIDR notation defines the prefix length.
Removing all access controls to streamline sharing
Why it's wrong here
Removing access controls would compromise confidentiality.
Public posting on the company website
Why it's wrong here
Public access contradicts confidentiality.
Common exam traps
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
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.
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
A developer is choosing between AES-256 (symmetric) and RSA-2048 (asymmetric) for encrypting a large file that will be sent to a partner. Symmetric encryption is fast but requires key exchange; asymmetric is slower but solves the key distribution problem. A hybrid approach — encrypt the file with AES, encrypt the AES key with RSA — is standard. Questions like this test whether you understand when each approach applies.
What to study next
Review block sizes, usable host formulas (2^n − 2), and how to find network and broadcast addresses for /24 through /30. Then practise related CISSP subnetting questions on CIDR, address ranges, and subnet selection.
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FAQ
Security and Risk Management — This question tests Security and Risk Management — CIDR notation defines the prefix length..
The correct answer is: Encryption at rest and in transit — Confidential data requires encryption both at rest and in transit to prevent unauthorized disclosure.
Review block sizes, usable host formulas (2^n − 2), and how to find network and broadcast addresses for /24 through /30. Then practise related CISSP subnetting questions on CIDR, address ranges, and subnet selection.
CIDR notation defines the prefix length.
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Last reviewed: Jun 24, 2026
This CISSP 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 CISSP exam.
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