What is Ntds.dit? - protege987/Active-Directory-Domain-Services GitHub Wiki

AD DS uses objects to store and reference data in the directory. The AD DS database file (Ntds.dit) provides the physical storage of all AD DS objects for a single forest. Although there is a single directory, some directory data is stored within domains while other data is distributed throughout the forest, without regard for domain boundaries.

Source: https://learn.microsoft.com/en-us/previous-versions/windows/it-pro/windows-server-2003/cc780036(v=ws.10)?redirectedfrom=MSDN