How to Check SQL Server Authentication Mode..?

DECLARE @AuthenticationMode INT

EXEC master.dbo.xp_instance_regread N'HKEY_LOCAL_MACHINE',

N'Software\Microsoft\MSSQLServer\MSSQLServer',

N'LoginMode', @AuthenticationMode OUTPUT

SELECT CASE @AuthenticationMode

WHEN 1 THEN 'Windows Authentication'

WHEN 2 THEN 'Windows and SQL Server Authentication'

ELSE 'Unknown'

END as [Authentication Mode]