Adding namespace server and replicating folder structure

Not sure if this is the correct forum. @mod, please redirect if applicable.

When adding a second or subsequent Namespace server to a DFS Root, how is the virtual folderstructure replicated when that server is added?

The folder-targets are stored in AD under the System container. However, folders (to create a sensible hierarchy) are not stored in AD. Where do they come from when a new Namespace server is added ?

Regards, Marcel