The answer is mask, because when a field like SSN matches the pattern for employee_id, the data is clearly sensitive PII that must be obscured while preserving its format for operational tasks such as testing or analytics. Masking irreversibly transforms the values, reducing exposure risk without breaking referential integrity, whereas encryption would leave the data recoverable by authorized users—an unnecessary capability for a field that only needs pattern matching. On the CISSP exam, this scenario tests your understanding of data lifecycle protection and the principle of least privilege; a common trap is choosing encryption because it seems more secure, but the key distinction is that masking is irreversible and format-preserving, making it ideal for non-production environments. Remember the memory tip: “Mask for format, encrypt for access”—if the field only needs to look real without being real, masking is the correct action.
CISSP Security and Risk Management Practice Question
This CISSP practice question tests your understanding of security and risk management. Match the stated requirement to the specific cloud service, access model, or configuration option — many options are valid in isolation but not for this scenario. 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 data classification policy is shown. A database contains a field labeled 'SSN' that matches the pattern for 'employee_id'. What action should be applied to the SSN field?
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Mask
The SSN field matches the pattern for 'employee_id', indicating it contains sensitive personally identifiable information (PII). Masking is the appropriate action because it preserves the data format for operational use (e.g., testing, analytics) while irreversibly obscuring the actual values, reducing exposure risk without breaking referential integrity. Encryption would still allow authorized decryption, which is unnecessary for fields that only need pattern matching, and blocking would prevent legitimate access to the field entirely.
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.
✗
None
Why it's wrong here
None is for public information.
✓
Mask
Why this is correct
Correct - The rule for employee_id pattern specifies mask.
Related concept
Read the scenario before looking for a memorised answer.
✗
Encrypt
Why it's wrong here
Pattern for credit_card_number is encrypt, not for employee_id.
✗
Block
Why it's wrong here
Block is not defined in the policy.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates often confuse 'encrypt' with 'mask', assuming encryption is always the best protection for sensitive data, but masking is specifically designed for fields that need to retain their format for operational use while preventing actual value disclosure.
Detailed technical explanation
How to think about this question
Masking techniques like substitution, shuffling, or data blurring replace sensitive values with realistic but fictitious data, ensuring the output retains the same length, character set, and format as the original (e.g., '123-45-6789' becomes 'XXX-XX-XXXX' or a random valid SSN pattern). In database environments, dynamic data masking (DDM) applies these transformations at query time based on user permissions, without altering the underlying storage, which is critical for compliance with regulations like GDPR or HIPAA. A real-world scenario is a development team needing realistic test data: masking allows them to use production-like data without exposing actual SSNs, whereas encryption would require key management and decryption overhead.
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 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.
Related glossary terms
Concepts from this question explained
These glossary pages explain the core terms tested in this CISSP question in full detail.
Security and Risk Management — This question tests Security and Risk Management — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: Mask — The SSN field matches the pattern for 'employee_id', indicating it contains sensitive personally identifiable information (PII). Masking is the appropriate action because it preserves the data format for operational use (e.g., testing, analytics) while irreversibly obscuring the actual values, reducing exposure risk without breaking referential integrity. Encryption would still allow authorized decryption, which is unnecessary for fields that only need pattern matching, and blocking would prevent legitimate access to the field entirely.
What should I do if I get this CISSP 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.
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Question Discussion
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