Where the user is Authenticated in Domain

[Sef]

Dear Gurus,

I want to know that where the domain user is authenticated and where the database is maintained.

for the local machine it is maintained in system32 folder config directory

but domain user whether it is updated, in local machine database or somewhere in domain

A domain user is authenticated by the domain controller. The short story is that If I'm logged on under a domain account, and then try to access another machine in the same domain (connecting to a shared network folder on that machine for instance), then that machine will send my credentials to the domain controller for authentication. The security database which stores my credentials (user name and password) is the domain controller itself (not the machine whose shared folder I'm trying to access in this case)