You have determined that the archiving was not successful in on of the destinators. You want to check the alert log file for more information on this. Which initialization parameter gives you the location of the alert log file?

The BACKGROUND_DUMP_DEST initialization parameter specifies the directory location for background process trace files, including the alert log (alert_.log). The alert log contains diagnostic information about database operations, errors, and archiving issues. USER_DUMP_DEST is for server process traces, CORE_DUMP_DEST for core dumps.