the Windows Recovery Environment (starting with Windows Vista). NTBackup can back up the registry as part of the System State and restore it. Automated System Recovery in Windows XP can also restore the registry. On Windows NT, the Last Known Good Configuration option in startup menu relinks the HKLM\SYSTEM\CurrentControlSet key, which stores hardware and device driver information. Windows 98 and Windows ME include command line (Scanreg.exe) and GUI (Scanregw.exe) registry checker tools to check and fix the integrity of the registry, create up to five automatic regular backups by default and restore them manually or whenever corruption is detected. The registry checker tool backs up the registry, by default, to %Windir%\Sysbckup Scanreg.exe can also run from MS-DOS. The Windows 95 CD-ROM included an Emergency Recovery Utility (ERU.exe) and a Configuration Backup Tool (Cfgback.exe) to back up and restore the registry. Additionally Windows 95 backs up the registry to the files system.da0 and user.da0 on every successful boot. Windows NT 4.0 included RDISK.EXE, a utility to back up and restore the entire registry. Windows 2000 Resource Kit contained an unsupported pair of utilities called Regback.exe and RegRest.exe for backup and recovery of the registry. Periodic automatic backups of the registry are now disabled by default on Windows 10 May 2019 Update (version 1903). Microsoft recommends System Restore be used instead. Policy Group policy Windows 2000 and later versions of Windows use Group Policy to enforce registry settings through a registry-specific client extension in the Group Policy processing engine. Policy may be applied locally to a single computer using gpedit.msc, or to multiple users and/or computers in a domain using gpmc.msc. Legacy systems With Windows 95, Windows 98, Windows ME and Windows NT 4.0, administrators can use a special file to be merged into the registry, called a policy file (POLICY.POL). The policy file allows administrators to prevent non-administrator users from changing registry settings like, for instance, the security level of Internet Explorer and the desktop background wallpaper. The policy file is primarily used in a business with a large number of computers where the business needs to be protected from rogue or careless users. The default extension for the policy file is .POL. The policy file filters the settings it enforces by user and by group (a "group" is a defined set of users). To do that the policy file merges into the registry, preventing users from circumventing it by simply