388.Flashback Database relies on which technologies to recover to a point in time?
A. Flashback Data Archive
B. Flashback logs in the flash recovery area
C. FlashbUndo tablespace
D. RMAN command line
E. None of the above
Answer: B
答案解析：
Enabling Flashback Database
To revert the entire database to a prior point in time, you can either revert the entire database to a prior point in time by restoring a backup and doing point-in-time recovery, or you can enable Flashback Database. When you enable Flashback Database, the database generates flashback logs in the fast recovery area. These logs are used to flash back the database to a specified time. During usual operation, the database occasionally logs images of data blocks to the flashback logs. The database automatically creates, deletes, and resizes flashback logs.
官方参考：http://docs.oracle.com/cd/E16655_01/server.121/e17643/backrest.htm#ADMQS12433
闪回开启及四种闪回类型的原理参考：http://blog.csdn.net/rlhua/article/details/11934831