Exam 1z0-062 topic 1 question 114 discussion

reference: https://docs.oracle.com/cd/B19306_01/backup.102/b14192/bkup004.htm#:~:text=A%20differential%20backup%2C%20which%20backs,incremental%20backup%20at%20level%200 "Each data block in a datafile contains a system change number (SCN), which is the SCN at which the most recent change was made to the block. During an incremental backup, RMAN reads the SCN of each data block in the input file and compares it to the checkpoint SCN of the parent incremental backup. If the SCN in the input data block is greater than or equal to the checkpoint SCN of the parent, then RMAN copies the block." "Block changing tracking improves the performance of incremental backups by recording changed blocks in the block change tracking file. During an incremental backup, instead of scanning all data blocks to identify which blocks have changed, RMAN uses this file to identify the changed blocks that need to be backed up."