Network-attached storage (NAS) is a file-level (as opposed to block-level storage) computer data storage server connected to a computer network providing data access to a heterogeneous group of clients. NAS is specialized for serving files either by its hardware, software, or configuration.
A network management system (NMS) is an application or set of applications that lets network administrators manage a network's independent components inside a bigger network management framework. NMS may be used to monitor both software and hardware components in a network. It usually records data from a network's remote points to carry out central reporting to a system administrator.
Direct-Attached Storage (DAS) refers to a digital storage system directly attached to a server or workstation, without a network in between.