Oracle DBA Tuning questions

I am doing a couple of practice exams for the DBA Tuning exam. Could people help me answer the following questions. I am unsure if I am right.

Sorry before people complain and say that this thread belongs in the Certification forum, it seems that that there no action in that forum. Which is why I posted my thread here.

Thanks in advance for any feedback.

1) Which two statements are true regarding running the Data Dictionary Cache? (Choose two)
A. The ratio of GETMISSES to GETS found in the V$ROWCACHE view should be less than 5 percent.
B. If the hit ratio for the library cache is acceptable, the hit ratio for the data dictionary should be also be acceptable.
C. On instance startup, the data dictionary cache contains no data, so any SQL statement is likely to result on cache misses.
D. On instance startup the data dictionary cache is automatically loaded with the most commonly used information, so many SQL statements will not cause cache misses.



2) You have been running SQL that requires sorts all day in your database. At the end of the day, you queried the V$SORT_SEGMENT view using this statement:

Select TABLESPACE_NAME, CURRENT_USERS, USED_EXTENDS, FREE_ENTENDS FROM V$SORT_SEGMENT

The statement returned NO rows.
What is a valid conclusion ?
A. All sort operations have completed in memory.
B. All sort operations went to the temporary tablespace.
C. The PRE_PAGE_SGA initialization parameter was set to TRUE.
D. All the sort operations went to the users’ default tablespace.


3) You are monitoring redo log performance using the query shown.

Select sid, event seconds_in_wait, stat
From v$session_wait
Where event = ‘log buffer space’;

This returned:
SID EVENT SECONDS_IN_WAIT STATE
5 log buffer space 110 Waiting

Which two options could solve your problem ? (Choose two)
A. Make the log buffer bigger.
B. Perform a commit more frequently
C. Increase the size of the log files
D. Add a disk controller to the file
E. Move the log files to a faster disk


4) Which two are true about buffer cache advisory ? (Choose two)
A. It is enabled by the DB_CACHE_ADVICE initialization parameter.
B. It estimates the number of physical writes to disk from the buffer cache.
C. It predicts the estimated number of indirect reads for different cache sizes.
D. It enables and disables statistics for predicting behavior with different caches sizes
E. The database should be shut down after enabling the DC_CACHE_ADVISOR to ensure that buffer cache statistics are reset.


5) Which three statements are true about the High-water mark? (Choose three)
A. It is reset by the truncate command
B. It is recorded in segment header block
C. It is set to the end of the segment on creation
D. It is set to the beginning of the segment on creation


6) Many applications insert in ascending index order and delete old values. In which case would you need to rebuild your indexes regularly ?
A. When the B-level is low
B. When index blocks contain many entries
C. When the high water mark has been reached
D. When the B-level is high and the index blocks contain very few entries

closed, duplicate.