Key concepts : Virtual domains (VDOMs) : Enabling the VDOM feature
 
Enabling the VDOM feature
By default, the VDOM item you use to create virtual domains is not visible and all administrators are assigned to the predefined root virtual domain.
To enable the VDOM feature, go to System > Admin > Settings, select Enable VDOM, and then click Save.
After you enable the VDOM feature, you can create additional virtual domains and assign administrators to them. The administrators see only the configuration and data for the virtual domain that you assign them to.
When the VDOM feature is enabled, the admin administrator accesses the configuration and data for all virtual domains (including root) under the Virtual Domain menu in the navigation pane.
To disable the VDOM feature:
Assign all network interfaces and administrators to the root virtual domain.
Delete all virtual domains.
Clear the Enable VDOM option.