Checking RAC / Non RAC

Wanted to confirm whether database was running RAC - easy way is to use

show parameter CLUSTER_DATABASE

or use the following:

Oracle Database 11g Release 11.2.0.3.0 - 64bit Production
SQL> BEGIN
  2    IF dbms_utility.is_cluster_database THEN
  3        dbms_output.put_line('Running in SHARED/RAC mode.');
  4    ELSE
  5        dbms_output.put_line('Running in EXCLUSIVE mode.');
  6    END IF;
  7  END;
  8  /
PL/SQL procedure successfully completed.

SQL> set serveroutput on
SQL> /
Running in EXCLUSIVE mode.
PL/SQL procedure successfully completed.

Also quick check :

cluvfy comp healthcheck

and node connectivity check

cluvfy comp nodecon -n ora01b,ora02b,ora03b,ora04b -verbose