Oracle ZFS Storage Appliance Security Overview
Network Information Service (NIS)
If no name-based mapping rule applies for a particular user, that user is given temporary credentials through an ephemeral mapping unless they are blocked by a deny mapping. When a Windows user with an ephemeral UNIX name creates a file on the system, Windows clients accessing the file using SMB see that the file is owned by that Windows identity. However, NFS clients see that the file is owned by “nobody”.