If the value of MaxPosPhaseCorrection on this domain controller is less than 48 hours, this domain controller might reject ...

If the value of MaxPosPhaseCorrection on this domain controller is less than 48 hours, this domain controller might reject accurate and genuine time updates from other time servers. If the value of MaxPosPhaseCorrection on this domain controller is greater than 48 hours, this domain controller will be able to adopt large fluctuations forward or backward in time which can cause problems throughout the domain.