For active dataguard:-
Create physical standby by following my post How to Create Physical Standby and then on Standby execute following:-
SHUTDOWN IMMEDIATE; STARTUP MOUNT; ALTER DATABASE OPEN READ ONLY; ALTER DATABASE RECOVER MANAGED STANDBY DATABASE DISCONNECT FROM SESSION;
That’s it, Now you can see that your physical standby is in read only mode, as promised by the Active DataGuard feature.
select name, open_mode, database_role from v$database;