WD Sentinel DS5100 4 TB Ultra-Compact Storage Plus Server (WDBYVE0040KBK-NESN) Ultra-compact and quiet design Powered by Windows Server 2012 R2 Essentials Integrated NAS and iSCSI SAN Support for running on-premise or cloud-based line-of-business applications Built-in Active Directory and Primary Domain Controller Enterprise grade backup and restore software (no additional license fees) Automatic backup and restore software for up to 25 users and 50 Windows or Mac client computers Built-in integration to cloud services