The Active Directory Database is Stored in %SYSTEM ROOT%\NDTS folder. Main database file for active directory is ntds.dit. Along with this file there are other files also present in this folder. These files are created when you run dcpromo. These are the main files controlling the AD structure
ntds.dit: This is the main database file for active directory.
edb.log: Transaction performed to ad stored in this file.
res1.log: Used as reserve space in the case when drive had low space.
res2.log: Same as res1.log.
edb.chk: This file records the transactions committed to ad database.
When a change is made to the Win2K database, triggering a write operation, Win2K records the transaction in the log file (edb.log). Once written to the log file, the change is then written to the AD database. System performance determines how fast the system writes the data to the AD database from the log file. Any time the system is shut down; all transactions are saved to the database.
During the installation of AD, Windows creates two files: res1.log and res2.log. The initial size of each is 10MB. These files are used to ensure that changes can be written to disk should the system run out of free disk space. The checkpoint file (edb.chk) records transactions committed to the AD database (ntds.dit). During shutdown, a "shutdown" statement is written to the edb.chk file. Then, during a reboot, AD determines that all transactions in the edb.log file have been committed to the AD database. If, for some reason, the edb.chk file doesn't exist on reboot or the shutdown statement isn't present, AD will use the edb.log file to update the AD database.
The last file in our list of files to know is the AD database itself, ntds.dit. By default, the file is located in\NTDS, along with the other files we've discussed