Hint
You're not able to control which redis replica will chosen for the failover.
- 
Connect to your sentinel instance:
redis-cli -p <SENTINEL-PORT> - 
Have a look at the configured masters, current master and the available replicas
INFO sentinelSENTINEL master <master name> SENTINEL get-master-addr-by-name <master name> # IP and port onlySENTINEL slaves <master name> - 
Force a failover
SENTINEL failover <master name> - 
After some seconds you can have a second look at the current master:
SENTINEL get-master-addr-by-name <master name>The IP should have changed.