- the Domain Functional Level (DFL) Elevation happens when all the Domain Controller (DC)s in the domain meet the minimum required OS version, unlocking newer AD functionality
- the Primary Domain Controller (PDC) Emulator is required for a DFL Elevation because AD changes need to be coordinated across all domain controllers. the pdc acts as the central point to validate, commit and replicate changes during the DFL elevation
- raising the DFL can enable better features like better SYSVOL Replication with DFSR and stuff