Changing the IP address of a Microsoft SQL server 2005 cluster is not hard but you need to make sure you’ve make the backups of the databases and other data.
In order to change the IP address of a working Microsoft SQL server 2005 cluster, we need to perform the following steps.
1. Shut-down one of the sql servers (SQL2) and Login to the other one (SQL1).
2. Open the cluster management console and Right click on cluster IP address and change the ip address to the new subnet.
3. Change the IP address of the SQL server virtual machine.
Incase you’ve made any changes to the windows hosts file make sure you update them with the new addresses.
4. Login to the Domain Controller
5. Change the IP address of the DC and the DNS server.
6. Update the DNS records of the servers; reload the DNS server.
7. Start the cluster on the SQL1 .
8. Login to the second server and change the ip/subnet.
9. At this point the sql cluster should be up and working on both the servers and you should only see the new network under the network resources in the cluster management console.
In order to check that the cluster is working correctly failover the cluster a couple of times.