Simple definition
VM Generation ID helps supported guest systems detect that a VM has been restored or cloned, avoiding unsafe state reuse.
Purpose and use
VM Generation ID lets a compatible guest detect selected changes in its VM generation.
How does it work?
The hypervisor exposes an identifier whose change can signal a supported state reversion or related event.
Example and verification
For directory-server recovery, verify support in both hypervisor and guest operating system.
Points to watch
It is neither a backup identifier nor blanket permission to restore any domain controller without an appropriate procedure.
In short
The signal helps compatible guests respond; it does not replace recovery validation.