The SQL Server 2000 Books Online documentation describes
many of the enhancements to the network libraries. Specifically, the ability to
dynamically determine ports for secondary instances.
SQL Server 2000
clients use DBNETLIB to perform to detect the ports. DBNETLIB is always loaded
by the ODBC or SQLOLEDB components. DBNETLIB is responsible for making either
direct IP/SPX calls or forwarding requests directly to the Shared Memory, Named
Pipes or other network libraries. DBNETLIB also handles the protocol preference
order when secondary protocol attempts are necessary.
Configuration Utility has been extended to provide an option for dynamic port
detection. When you enable the Client Configuration Utility, no port number is
stored for the alias entry and DBNETLIB attempts to contact the server through
a known UDP port to obtain the correct connection information.
Note Dynamic port detection is only aavailable for named
instances of SQL Server 2000. The behavior of SQL Server 2000 for a default
instance is exactly the same as in earlier versions of SQL Server. The network
libraries assume either 1433 or the global default port established with the
Client Configuration Utility.
If a default instance is listening on
a port other than the standard 1433 port, you can
provide an alias or change the global default port.
You can also connect to the instance of SQL Server by using its server name, its FQDN, or its IP
address followed by a comma and the port number.