Subsequent messages are exchanged by using a combination of file access and LDAP. The Group Policy: Core Protocol allows Group Policy clients and administrative tools to access policy instructions stored on the Group Policy server. The Client and administrative tools use file access and LDAP as transports to access that storage, which itself is split between network file system storage and Active Directory. Group Policy defines specific file formats and directory structure layouts that define the structure of the file system storage.
Similarly, Group Policy also defines objects with specific schemas that are stored in Active Directory of the Group Policy server, and Clients and administrative tools use LDAP to access Active Directory to obtain these structured objects. Almost all of the data that is exchanged in a Group Policy protocol conversation consists of file access and LDAP as the transports for conveying the Group Policy: Core Protocol.
For the structure of the files and Active Directory objects, see section 2.2.