I was configuring a client yesterday for a SQL Server 2005 Express DB. Before building the ODBC connect string, I ran ping <IP Address>; the server replied. I then ran TELNET <IP Adress> 1433 (1433 being the SQL over TCP port number). I received the following response: "Connecting To <IP Address>...Could not open connection to the host, on port 1433:" Here's the weird part, I tried the ODBC connect string, and it worked. I double-checked, the host name specified in the ODBC connect string does match the IP address. Up until yesterday, I'd assumed that port 1433 had to be open on the SQL server for a client / server connection to be successful. Am I wrong. Or, is my understanding of TELNET as a "port pinger" flawed.