Mid-level DBA

1) When you enter 'sqlplus scott/tiger' which background process checks for authentication ? From which table/view it checks for authentication ? If password is wrong from where oracle throws the msg ?
2) If you create a permanent tablespace and allot it to 5 users as temporary tablespace, how many extents will be allocated by oracle for each user ?
3) When redo log contains both roll forward and rollback entries, why you require a separate rollback segment ?
4) When you insert or import 8 GB of data and your rollback segment is of 100 MB size (without autoextend), then what will happen to the transaction? During inserts or import what entries will goto rollback segment ?
5) When deferred rollback segment is used ?
6) Is it possible to change ownership of Process IDs from oracle to the user who have invoked the process (for example all scott user processes are owned by Oracle user when you check in unix ps -ef grep oracle command). Why the PIDs are owned by Oracle instead of the user who has invoked it ?
7) What are the other reasons for ORA-1555 error except rbs size is small ?
8) After starting database, where will the dictionary files will reside (memory or system tablespace datafile). If your answer is memory, then whether all the v$ and x$ and other dictionary files are loaded in memory ? ( I answered that it depeneds upon the size of SGA).
9) Where freelists are stored ?
10) Is 'direct_io' parameter is equal to raw