Problem Description:

After a NIC change of the Server there were issues with starting the SQL Server services and it was failing to start. The error it was throwing was:

Error:
Could not find any IP address that this SQL Server instance depends upon.  Make sure that the cluster service is running, that the dependency relationship between SQL Server and Network Name resources is correct, and that the IP addresses on which this SQL Server instance depends are available.  Error code: 0x6d9

Environment
SQL Server 2005 (Enterprise Edition)  SP2 64 bit
Windows 2003 Enterprise Server  SP 2 
NO CLUSTER

Resolution:

Ø The error message looked like the SQL Cluster Name’s IP address was not found
Ø But surprisingly we got to know that the SQL is not on a Cluster
Ø Checked the Cluster Services”: Not present. Cluster admin not configured
Ø Question is So how are we picking the Cluster Information for SQL then..
Ø I went ahead and checked the registry and there was it, we had the Cluster key present with a Virtual SQL Server Name {which is the same as the name of the windows machine}, this key should be only present if you have a Cluster not in a Standalone Machine
HKLM\Software\Microsoft\Microsoft SQL Server\MSSQL.1\Cluster {this key was existing}
Ø This can be because of someone might have tried to install SQL as a Cluster resource
Ø We deleted the Cluster key and then we were able to start the SQL Server Services from the Services.msc without any issues.