V$PASSWORDFILE_INFO
V$PASSWORDFILE_INFO provides information about the database password file.
select * from v$passwordfile_info;
show parameter remote_login_passwordfile;
Remote_login_passwordfile Parameter and it’s use
Remote_login_passwordfile specifies whether Oracle checks for a password file . When we grant “sysdba” or “sysoper” privileges to a user, that user’s name and privilege information are added to the password file. A user’s name remains in the password file only as long as that user has at least one of these two privileges. If we revoke both of these privileges, Oracle Database removes the user from the password file .
We have two options for Super User “SYS” password authentication .
1.) Operating System authentication
2.) Password file authentication
Posted from : https://neeraj-dba.blogspot.com/2011/03/remoteloginpasswordfile.html
In one of your databases, user KING is:
1. Not a DBA user
2. An operating system (OS) user
Examine this command and its output:

What must you do so that KING is authenticated by the OS when connecting to the database instance?
- A. Set OS_AUTHENT_PREFIX to OPS$
- B. Have the OS administrator add KING to the OSDBA group
- C. Grant DBA to KING
- D. Unset REMOTE_LOGIN_PASSWORDFILE
- E. Alter user KING to be IDENTIFIED EXTERNALLY