In order to change the Virtual IP of the sql server 2000 clustered instance we need to follow the following KB article
However If we try to change the Virtual IP by mapping the Virtual Server Name of the sql server resource to the New Virtual IP in the DNS alone then sql server resource may fail to come online giving the following message in the error log and the application event log
2008-06-30 15:48:24.51 server SuperSocket Info: Bind failed on TCP port 5184.
In the above case the Virtual IP was registered against the Virtual Server Name of the sql server in the DNS.
However the following registry value still contained the old IP address
Because the registry value contained the old IP address. When the resource was tried to bring online from the cluster admin. The cluster service was trying to bind sql server resource to the TCP port 5184 of the old IP Address. Because the previous IP address was nonexistent we were not able to bind on the port <old IP address>:5184
In order to resolve this and bring sql server resource online we need to modify the registry key
to store the New value of Virtual IP address