In a working environment, you normally log into a domain-joined computer using a domain assigned account. The username you use in the login screen is from an account assigned from the domain, not the local account on the local computer.

Normally, you don’t need to use a local account on a domain-joined computer in anyway because if you need a local admin rights to do something, you can still use a domain admin account to do so.
However, in some situations where you really need to log in as a local account, you click Other Users in the login screen and use the following format as the username.
computername\username
But the problem is, I don’t always know the computer name of the computer I need to work on. And now, here is the trick I wish I would have known a long time ago. Instead of typing the computer name, use this instead.
.\username
Simply, easy, and it even tells you what the computer name is right after you typed “.\” in the username field.
