Changing the IP address on your nodes is as easy as it sounds, Change the IP in the
cassandra.yaml on all nodes then do a restart of the service.
After all nodes that have had their IP's changed have been restarted, and you verify that Cassandra is communicating as normal, verify that the old IP's are not in the
system.peers table in CQLSH.
to check this run on all nodes:
|cqlsh> SELECT * FROM system.peers;|
If the old IP's are showing up in the system.peers then you can remove them from each node with:
|delete from system.peers where peer = '<IP address>';|