Microsoft Windows caches previous users’ logon information locally so that they can log on if a logon server is unavailable during later logon attempts.
If a domain controller is unavailable and a user’s logon information is cached, the user will be prompted with a dialog that says:
A domain controller for your domain could not be contacted. You have been logged on using cached account information. Changes to your profile since you last logged on may not be available.
With caching disabled, the user is prompted with this message:
The system cannot log you on now because the domain <DOMAIN_NAME> is not available.
When you logon to Windows by using cached logon information, if the domain controller is unavailable to validate your account, you cannot access network resources that require domain validation. However, you can access network resources that do not require domain validation.