You can save it as VM, but you can also try granular approach which is offered by NMM module.

If I want save all VM how is it working? Is it temporary stopping VM, creating clone and starting VM starting again?

I think that stopping is compulsory because at this momend sombedy Can work on this Active Directory.

I believe it uses VSS to create consistent snapshot beneath or to freeze VM for VMWare snapshot which is backed up then. As far as I know, in docs there should be dedicated chapter to AD protection so that one might have more details.

Hi Debek, it does not stop virtual machines, if you decide to take vba approach it takes snapshot of machine without shutdown - interruption between disk/os/vmware are too short (literally milliseconds) to cause any downtime (it was goal of vba to have back up without downtime). But like Hrvoje Crvelin said to have AD consistent state I would use on top of vm backup NMM module.