oracle service not starting on correct node
I have 3 node 12c rac cluster and created the following service
oracle-rac1:/home/oracle/scripts> srvctl add service -db rac -service rac23 -preferred rac2,rac3 -available rac1 -tafpolicy BASIC
oracle-rac1:/home/oracle/scripts> srvctl start service -db rac -service rac23
oracle-rac1:/home/oracle/scripts> srvctl status service -d rac
Service rac23 is running on instance(s) rac1,rac2
preferred rac2,rac3
available rac1
Question: why the service rac23 did not start on rac2 and rac3 ?