Book excerpt: NFS Version 4 (NFS V4) is the latest defined client-to-server protocol for NFS. A significant upgrade from NFS V3, it was defined under the IETF framework by many contributors. NFS V4 introduces major changes to the way NFS has been implemented and used before now, including stronger security, wide area network sharing, and broader platform adaptability. This IBM Redbooks publication is intended to provide a broad understanding of NFS V4 and specific AIX NFS V4 implementation details. It discusses considerations for deployment of NFS V4, with a focus on exploiting the stronger security features of the new protocol. In the initial implementation of NFS V4 in AIX 5.3, the most important functional differences are related to security. Chapter 3 and parts of the planning and implementation chapters in Part 2 cover this topic in detail.