Windows 2000 introduced the idea of system-state components, a collection of interdependent system components that you back up and restore as a single entity. System-state components on a Win2K domain controller (DC) include the following:
AD. The physical files that comprise Active Directory (AD) include ntds.dit (the AD database), edb.chk (the Jet database checkpoint file), edb*.log (the AD transaction log files, each of which is 10MB), and res1.log and res2.log (the two reserved placeholder transaction log files).
Registry. The registry's contents are automatically backed up when you back up system-state data. The system saves an additional copy of the registry hive files in the \%systemroot%\repair\regback folder; you can use this copy to restore the registry without performing a complete system-state restore.
AD-Integrated DNS Zone Data. In AD-integrated DNS zones, the system backs up zone data as part of the AD database. If you don't have an AD-integrated DNS, back up the zone files separately. However, when you back up the system disk along with the system-state data, the system will back up zone data as part of the system disk.
System Boot Files. Win2K requires system boot files to boot.
COM+ Class Registration Database. The system-state data backs up and restores the COM+ services class registration database.
Sysvol. The system volume (sysvol) provides a standard location on a Win2K DC for files that must be shared for common access throughout a domain. Sysvol also includes the NetLogon share (which hosts items such as logon scripts and system policies for non-Win2K systems), NTFS junctions, user logon scripts, Win2K Group Policy data, and File Replication Service (FRS) staging directories.
Cluster Services and Certificate Services Data. If you've installed Microsoft Cluster services or Microsoft Certificate Services on your DC, their data (which includes the cluster quorum log and Certificate Services database) will be part of the system-state data.