If the domain controller is unavailable, will the user be able to log in to the system?

If the domain controller (for example, Active Directory Domain Controller) is unavailable, the user's ability to log in depends on the settings and type of authentication:

• Cached credentials: modern operating systems (such as Windows) cache the data of the last successful login. If the controller is unavailable, the user can log in using cached data, but with limitations (for example, without access to network resources).

• Local accounts: if the user uses a local account on the machine, login is possible without contacting the controller.

• Network authentication: if credential verification on the controller is required (for example, during the first login or password change), login will be impossible.

Thus, when the domain controller is unavailable, the user can log in if their credentials were previously cached or if a local account is used. Otherwise, login will be blocked until the connection to the controller is restored.