use DBI; 
$DSN = "my_datasourcename"; # Name of the DSN referring to the remote MSSQL-database with IP-adress, logins etc. 
$dbh = DBI->connect("dbi:ODBC:$DSN;or die "$DBI::errstr\n";

##</code><code>##

use DBI;
# Test code for connecting directly to a remote MSSQL database WITHOUT a predefined data source name... 
$database = "TempoPlan"; 
$hostIP = "111.222.333.444"; # Example IP-adress for this post
$port = "1433"; 
$servername = "MSSQL_SERVERNAME"; 
$user = "username"; 
$password = "password"; 

$DSN = qq|driver={SQL Server (32 bit)};Server=$servername; database=$database;port=$port;uid=$username;pwd=$password;|; 
$dbh = DBI->connect("dbi:ODBC:$DSN;host=$hostIP;") or die "$DBI::errstr\n";

##</code><code>##

DBI connect('driver={SQL Server (32 bit)};Server=MSSQL_SERVERNAME; database=TempoPlan;uid=username;pwd=password;;host=111.222.333.444;','',...) failed: [Microsoft][ODBC Driver Manager] Data source name not found and no default driver specified