<P> A full - featured operating system is not needed on a NAS device, so often a stripped - down operating system is used . For example, FreeNAS or NAS4Free, both open source NAS solutions designed for commodity PC hardware, are implemented as a stripped - down version of FreeBSD . </P> <P> NAS systems contain one or more hard disk drives, often arranged into logical, redundant storage containers or RAID . </P> <P> NAS uses file - based protocols such as NFS (popular on UNIX systems), SMB / CIFS (Server Message Block / Common Internet File System) (used with MS Windows systems), AFP (used with Apple Macintosh computers), or NCP (used with OES and Novell NetWare). NAS units rarely limit clients to a single protocol . </P> <P> The key difference between direct - attached storage (DAS) and NAS is that DAS is simply an extension to an existing server and is not necessarily networked . NAS is designed as an easy and self - contained solution for sharing files over the network . </P>

7. what are the name of the protocols used by network attached storage(nas)