Before RAC:
----------- 
       DB:  The name of the single DB which was running on port 1522 on node01.
 

After our DBA configured the RAC in the DB, I have three more instances:
-----------------------------------------------------------------------
       

      Now I see : DB1 ? servs to what I don't know ... I don't see the process corresponding to this instance (may be visible in the grid !).
      hostname1-scan

      He switched from 1522 to 1521 (1522 had some troubbles of connection).    
       
      I can see the first listener called: $ORACLE_HOME/bin/tnslsnr DB -inherit

 
node01:
-------
DB11
hostname1-vip
hostname1-scan

node02:
-------
DB12
hostname1-vip
hostname1-scan



SQL> show parameter service 
service_names                        string      DB1, ebs_patch
SQL> show parameter listener
listener_networks                    string
local_listener                       string      hostname1-vip:1521
remote_listener                      string       hostname1-scan:1521

second node of the RAC:

SQL> show parameter service
service_names                        string      DB1, ebs_patch
SQL> show parameter listen
listener_networks                    string
local_listener                       string      hostname2-vip:1521
remote_listener                      string       hostname1-scan:1521