To make changes available to all administrators, and to unlock the objects and rules that are being edited, the administrator must publish the session.
To make your changes available to other administrators, and to save the database before installing a policy, you must publish the session. When you publish a session, a new database version is created.
When you selectInstall Policy, you are prompted to publish all unpublished changes. You cannot install a policy if the included changes are not published.

Explanation/Reference:
Explanation :
AD Query extracts user and computer identity information from the Active Directory Security Event Logs.
The system generates a Security Event log entry when a user or computer accesses a network resource.
For example, this occurs when a user logs in, unlocks a screen, or accesses a network drive.
Reference : https://sc1.checkpoint.com/documents/R76/CP_R76_IdentityAwareness_AdminGuide/62402.htm

VPN communities are based on Star and Mesh topologies. In a Mesh community, there are VPN connections between each Security Gateway. In a Star community, satellites have a VPN connection with the center Security Gateway, but not to each other.

Authentication Schemes :- Check Point Password
- Operating System Password
- RADIUS
- SecurID
- TACAS
- Undefined If a user with an undefined authentication scheme is matched to a Security Rule with some form of authentication, access is always denied.