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A SQL Server client may not be able to connect to SQL Server in a cluster environment using the virtual server network name or IP address by means of TCP/IP sockets. A typical client application will return the following error message:
Unable to Connect: SQL Server is unavailable or does not exist. General
network error. Check your documentation.
Net-Library error 10061: ConnectionOpen (Connect())
However, the same socket client can connect to the SQL Server using the node name or address of the computer where SQL Server is physically running. Clients running named pipes do not have this problem of connecting to SQL Server through the virtual server name.
There is a known problem with Windows NT 4.0 Enterprise Edition that may return an incorrect IP address under certain situations when an application such as SQL Server calls socket function gethostbyname() to retrieve the virtual server IP address from the local node. When SQL Server is bound to this incorrect IP address (node address), a socket client will not be able to connect to the SQL Server through the virtual name or IP address, but can connect to it through node name or IP address.
One way to verify whether you have run into this issue is to PING the SQL Server virtual server name from the command prompt on the node computer where SQL Server is currently running. If PING returns the node IP address rather than the SQL Server virtual server IP address, then you have run into this problem. Note that if you PING this virtual server name from a separate network client computer, it returns the correct IP address.
To resolve this problem, obtain the latest service pack for Windows NT 4.0 or Windows NT Server 4.0, Terminal Server Edition. For additional information, click the following article number to view the article in the Microsoft Knowledge Base:
(https://support.microsoft.com/kb/152734/EN-US/ )How to Obtain the Latest Windows NT 4.0 Service Pack
You can work around this problem by using named pipes for client connections.
Microsoft has confirmed that this is a problem in Windows NT 4.0 and Windows NT Server 4.0, Terminal Server Edition. This problem was first corrected in Windows NT 4.0 Service Pack 4.0 and Windows NT Server 4.0, Terminal Server Edition Service Pack 4.