I\'ve just started working with Cassandra (datastax), version 2.1.3 and cqlsh version 5.0.1.
Cassandra starts up fine and the cluster is operational instantly.
For me it turned out that the service wasn't running at all. Check with
service cassandra status
If you got the same error as I got, or another type, then messing around with IP addresses won't solve your problem at all.
The error I got:
cassandra dead but pid file exists
Edit: This was the solution for my problem: https://stackoverflow.com/a/46743119/3881406