Check the archive log status in Oracle Data guard

Check the received and applied archive log on the Oracle Dataguard environment

select 'Last Log applied : ' Logs, to_char(next_time,'DD-MON-YY:HH24:MI:SS') Time from v$archived_log where sequence# = (select max(sequence#) from v$archived_log where applied='YES')
union 
select 'Last Log received : ' Logs, to_char(next_time,'DD-MON-YY:HH24:MI:SS') 
Time from v$archived_log where sequence# = (select max(sequence#) from v$archived_log);

Find the last applied log on Standby Server:

select to_char(max(FIRST_TIME),'hh24:mi:ss dd/mm/yyyy') FROM 
V$ARCHIVED_LOG where applied='YES';

Find out the last seq received and applied in Dataguard

SELECT al.thrd "Thread", almax "Last Seq Received", lhmax "Last Seq Applied" FROM (select thread# thrd, MAX(sequence#) almax FROM v$archived_log WHERE resetlogs_change#=(SELECT resetlogs_change# FROM v$database) GROUP BY thread#) al, (SELECT thread# thrd, MAX(sequence#) lhmax FROM v$log_history WHERE resetlogs_change#=(SELECT resetlogs_change# FROM v$database) GROUP BY thread#) lh WHERE al.thrd = lh.thrd;