Compensating Controls Definition and Purpose
* A compensating control is an alternate measure that satisfies the intent of a specific PCI DSS requirement and provides an equivalent level of security.
* The rationale and risk mitigation must be explicitly documented using the Compensating Control Worksheet (CCW).
Mandatory Documentation
* PCI DSS v4.0 mandates the use of a CCW when implementing compensating controls. This applies regardless of acquirer approvals.
* The CCW requires detailed documentation including:
* Constraints preventing the original requirement from being implemented.
* Justification for the compensating control.
* Description of the control and evidence of its effectiveness.
Using Existing Requirements
* If an existing PCI DSS requirement (e.g., Requirement 5 for antivirus) is already implemented and can mitigate the risks of not meeting another requirement, it may qualify as a compensating control.
Approval and Review Process
* QSAs must validate the implementation, effectiveness, and appropriateness of compensating controls during the assessment process

According toRequirement 3.5.1.2, whendisk-level encryptionis used (e.g., full disk encryption), access control must beseparate from the operating systemto prevent unauthorised users from bypassing controls by booting the system.
* Option A:#Correct. Disk encryption must useindependent authentication mechanisms.
* Option B:#Incorrect. Sharing authentication with the OSviolates independence.
* Option C:#Incorrect. Association with local accounts may not ensure separate access control.
* Option D:#Incorrect. Key storage within user accounts is not secure or compliant.
Reference:PCI DSS v4.0.1 - Requirement 3.5.1.2 and its Applicability Note.

Requirement 8.4.2defines multi-factor authentication (MFA) asauthentication that requires at least two of the following:
* Something you know (password/PIN)
* Something you have (smart card/token)
* Something you are (biometric)
* Option A:#Incorrect. Presenting the same token twice is stillsingle-factor.
* Option B:#Incorrect. Two passwords arestill one factor- "something you know".
* Option C:#Correct. Password (something you know) + smart card (something you have) =MFA.
* Option D:#Incorrect. Fingerprint and thumbprint are bothbiometrics, so one factor.
Reference:PCI DSS v4.0.1 - Requirement 8.4.2 and Glossary definition of MFA.

According toRequirement 1.2.1of PCI DSS v4.0.1, network security controls (NSCs), such as firewalls and segmentation controls, are used torestrict and control trafficbetween trusted and untrusted networks. This includes logical or physical network segmentation.
* Option A:Incorrect. Anti-malware is addressed in Requirement 5.
* Option B:Correct. NSCs control and restrict inbound and outbound traffic between logical and physical network segments.
* Option C:Incorrect. Vulnerability management is under Requirement 6.
* Option D:Incorrect. PAN encryption is covered in Requirement 3.5.
Reference:PCI DSS v4.0.1 - Requirement 1.2.1.

PerRequirement 10.6.1, PCI DSS mandates that time-synchronization technology be used, andsystems must be synchronized to a central time serverthat itself receives time from an approved external source. This ensures logs can be accurately correlated.
* Option A:Incorrect. Time inconsistency arises if each system operates independently.
* Option B:Incorrect. Time configuration must berestricted to authorised personnel only.
* Option C:Correct. Time should be sourced from a centralised server which is in sync with reliable external sources.
* Option D:Incorrect. Each system peering independently can cause inconsistencies.
Reference:PCI DSS v4.0.1 - Requirement 10.6.1.1.