The domain for a set of credentials can be either for an Active Directory domain or a local user account.
Active Directory Domain
Simply enter the name of the domain to use. This can be either in short or fully qualified format (e.g. TEST.ADMINARSENAL.LOCAL). When used on a remote computer, such as when using PDQ Deploy to deploy software, the domain must be visible and usable from the target computer.
Local accounts are those which exist on the target computer in question. An account is considered local when the domain is left blank or contains a single dot (.) The use of the . prefix is mainly used to distinguish between local users with the same name, but different passwords on different computers. (The Description attached to Credentials serves the same purpose).
For PDQ Inventory 2.0 / Deploy 2.1 or higher these credentials will use the Administrator account on the local target.
These credentials specify the user al.swearengen in the deadwood.local domain
For PDQ Deploy 2.0.x or lower the credentials below will use the local Administrator account on the target computer. (notice the domain field does not exist in the earlier versions)
For PDQ Deploy 2.0.x or lower the credentials below would run the Al.Swearengen account in the deadwood.local domain