Determine whether mixed mode auth is enabled without logging in? Is it possible in SQL Server to determine whether mixed mode authentication is enabled without logging on to SQL Server?
You can check it in the registry:

HKLM\Software\Microsoft\Microsoft SQL Server\ [instancename] \MSSqlServer


The current mode is recorded in the LoginMode key.

Values (DWORD) can be:


1 = Windows Authentication mode
2 = SQL Server and Windows Authentication mode


Note: 


0 is equivalent to 2
You still need access to the Registry (and the server)