Prerequisite is ownership or purchase of Data Protector Express Backup Server. This is required for all file and application server class machines (defined by operating system) that are backed up over the LAN to the Data Protector Express Backup Server or a Data Protector Express Media Server. Unless the machine is running the Backup Server, if the machine is backed up to a locally attached tape device, then a Media Server LTU is required. In this case a Network Client Agent is not needed because the Media Server provides the connection to the Backup Server.