I use v$archived_log to check mine standby :
SQL> archive log list; Database log mode Archive Mode Automatic archival Enabled Archive destination USE_DB_RECOVERY_FILE_DEST Oldest online log sequence 5069 Next log sequence to archive 0 Current log sequence 5071 SQL>
Against my Primary I get the last log :
SELECT name as STANDBY, SEQUENCE#, applied, completion_time from v$archived_log WHERE DEST_ID = 2 AND NEXT_TIME > SYSDATE -1;
Data Guard has a set of v$ views to check results, 8archive log list8 isn't so good since with Data Guard you have two copies of the same database in different roles.
select max(sequence#) from v$archived_log where NEXT_TIME > sysdate -1;
The Oracle doc E10700-02 has several example in chapter 9 "Monitoring Primary, Physical Standby, and Snapshot Standby Databases"
select process, status, sequence#, block# from v$managed_standby;