多选题Which three statements are true regarding the logical structure of the Oracle database？（）AEach segment contains one or more extents.BMultiple tablespaces can share single data file.CA data block is the smallest unit of I/O for data files.DIt is possibl

第1题：

Which tow statements are most correct regarding opt-in models?（）

• A、A based opt-in model uses virtualized identifiers
• B、A based opt-in model uses hardware values as identifiers
• C、A logical server opt-in model uses virtualized identifiers
• D、A logical server opt-in model uses hardware values as identifiers

第2题：

Which three statements about the secure domain router are true？（）

• A、The logical router can span across chassis.
• B、The fabric and system controller module are shared by all logical routers.
• C、Each logical router has a distinct fabric and system controller module
• D、The logical router can share a route processor
• E、The logical router cannot share a route processor

第3题：

第4题：

Which two statements are true regarding L2TP? （）(Choose two.)

• A、Tunnels are initiated by the LAC
• B、Tunnels are initiated by the LNS
• C、By default, subscriber authentication occurs on the LNS
• D、By default, subscriber authentication occurs on the LAC

第5题：

Which statement is true regarding the INTERSECT operator?（）

• A、It ignores NULL values 
• B、Reversing the order of the intersected tables alters the result 
• C、The names of columns in all SELECT statements must be identical 
• D、The number of columns and data types must be identical for all SELECT statements in the query 

第6题：

Which three statements about OSPF areas are true?（）

• A、Areas introduce a boundary on the link - state updates.
• B、Areas are  logical definitions specific to any given router.
• C、All routers within an area have the exact link - state database.
• D、The calculation of the Dijkstra algorithm on a router is limited to changes within an area.
• E、The area designated router will always  have a priority of 0.

第7题：

Which of the following statements is true regarding the VERSIONS BETWEEN clause？（）  

• A、 The VERSIONS BETWEEN clause may be used in DML statements.
• B、 The VERSIONS BETWEEN clause may be used in DDL statements.
• C、 The VERSIONS BETWEEN clause may not be used to query past DDL changes to tables.
• D、 The VERSIONS BETWEEN clause may not be used to query past DML statements to tables.

第8题：

Which two statements are true regarding the USING clause in table joins?（）

• A、It can be used to join a maximum of three tables 
• B、It can be used to restrict the number of columns used in a NATURAL join 
• C、It can be used to access data from tables through equijoins as well as nonequijoins 
• D、It can be used to join tables that have columns with the same name and compatible data types

第9题：

Which of the following a true statements regarding the use of VLANs to segment anetwork? （）

• A、They increase the size of collision domains
• B、They allow logical grouping of users by function.
• C、They can enhance network security.
• D、They increase the size of the broadcast domain while decreasing the number of collision domains.
• E、They increase the number of broadcast domains while decreasing the size of the broadcast domains.
• F、They simplify switch administration.

第10题：

Which two statements are true regarding B-tree indexs（）

• A、The leaf blocks in the index are doubly linked.
• B、The leaf node stores a bitmap for each key value.
• C、The rows with NULL value in key columns also have entries in the index.
• D、The deletion of a row from the table causes a logical deletion in index leaf block and the space becomesavailable for the new leaf entry