this script creates the dsn using sql server authentication. what i need is windows authentication.

Unless I'm wrong, the "SQL Server" refered to in:

my $result = Win32::ODBC::ConfigDSN(
    ODBC_ADD_DSN, "SQL Server", ## this last is the driver name
    ( ##options
      "DSN=$dsn",           ## DSN identifier
      "NETWORK=DBMSSOCN",   ## use TCP/IP library
      "SERVER=test_server", ## server name
      "DATABASE=test_db",   ## database name
      "DESCRIPTION=My test DSN"
    )
  ); ## end of ConfigDSN call
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is a reference to the driver, NOT the authentification; it says as much in the code, itself. The authentification for who's allowed to create the DSN is based on, basically, the login that runs the program.