A local ISP hosts our SQL Server, and I haven't been able to see or connect to named instances running on the machine. I know that SQL Server 2000 named instances don't use TCP/IP port 1433, and I've verified that the TCP/IP ports that the SQL Server instances are using are open. Do you have any suggestions?
A Many people know how to check which ports SQL Server instances are listening to by using the SQL Server Network Utility or by simply reading the SQL Server error log. But many people seem to forget, or simply don't know, that UDP port 1434 also needs to be open to ensure that you can correctly access and browse named instances. I encourage you to read up on this requirement. Searching SQL Server Books Online (BOL) for "1434" returns three valuable hits. You'll also find information about accessing named instances in my SQL Server Savvy column from July 2001, InstantDoc ID 21127. For now, here's a simple explanation. SQL Server establishes a listener service on UDP port 1434 that lets a client query the server for a list of named instances and their network configuration information. This listener service always runs on UDP port 1434 and can't be configured to run on another port.