Which two statements are correct about database transportation?（） (Choose two.)

A .  The bus is limited to 32 devices B .  It is a full duplex serial standard C .  It is a half-duplex serial standard D .  It allows up to 320 MB/s of shared channel bandwidth

A . Zoning increases security. B . DNS queries are used for software zoning. C . Software zoning is more secure than hardware zoning. D . When using zones and VSANs together, the zone is created first. E . Zoning requires that VSANs be established before it becomes operational.

A . A single row subquery can retrieve data from only one table. B . A SQL query statement cannot display data from table B that is referred to in its subquery, unless table B is included in the main query's FROM clause. C . A SQL query statement can display data from table B that is referred to in its subquery, without including table B in its own FROM clause. D . A single row subquery can retrieve data from more than one table. E . A single row subquery cannot be used in a condition where the LIKE operator is used for comparison. F . A multiple-row subquery cannot be used in a condition where the LIKE operator is used for comparison.

A . A subquery that defines a view cannot include the GROUP BY clause  B . A view that is created with the subquery having the DISTINCT keyword can be updated  C . A view that is created with the subquery having the pseudo column ROWNUM keyword cannot be updated  D . A data manipulation language (DML) operation can be performed on a view that is created with the subquery having all the NOT NULL columns of a table

A . WRED can selectively discard lower priority traffic when the interface becomes congested and can provide differentiated performance characteristics for different classes of service. B . Resource Reservation Protocol （RSVP） and WRED cannot be configured on the same interface. C . WRED will throttle back voice traffic only as a last resort. D . If the average queue length is greater than the minimum threshold but less than the maximum threshold， then based on the drop probability， WRED will either queue the packet or perform a random drop. E . WRED statistically drops more packets from low-bandwidth users than high-bandwidth users. Therefore， traffic sources that generate the least traffic are more likely to be slowed down than traffic sources that generate the most traffic. F .  WRED treats non-IP traffic as precedence 4.

A . Clearing an alert sends the alert to the alert history. B . Response actions cannot be specified with server-generated alerts. C . The nonthreshold alerts appear in the DBA_OUTSTANDING_ALERTS view. D . Server-generated alerts notify the problems that cannot be resolved automatically and requireadministrators to be notified.

A . The application will crash. B . The code on line 29 will be executed. C . The code on line 5 of class A will execute. D . The code on line 5 of class B will execute. E . The exception will be propagated back to line 27.

A . The checkpoint frequency decreases with the smaller redo log file size. B . It ensures that all committed data is written to the data files during normal shutdown. C . The frequent full checkpoint in a database can cause the overall degradation of the database performance. D . It prompts the Checkpoint （CKPT） process to write data to the data files and redo information to the online redo log files.

A . Listeners use only the TCP/IP protocol. B . Multiple listener processes can run simultaneously on a host. C . Multiple database instances can be registered with a single listener. D . The listener-related errors can be traced only at the administrative level. E . Only one database instance can be registered with a single listener at any time.

A . The UNIQUE constraint does not permit a null value for the column. B . A UNIQUE index gets created for columns with PRIMARY KEY and UNIQUE constraints. C . The PRIMARY KEY and FOREIGN KEY constraints create a UNIQUE index. D . The NOT NULL constraint ensures that null values are not permitted for the column.

A .  Zoning increases security. B .  DNS queries are used for software zoning. C .  Software zoning is more secure than hardware zoning. D .  When using zones and VSANs together， the zone is created first. E .  Zoning requires that VSANs be established before it becomes operational.

A . You use a NEXTVAL pseudo column to look at the next possible value that would be generated from a sequence, without actually retrieving the value. B . You use a CURRVAL pseudo column to look at the current value just generated from a sequence, without affecting the further values to be generated from the sequence. C . You use a NEXTVAL pseudo column to obtain the next possible value from a sequence by actually retrieving the value from the sequence. D . You use a CURRVAL pseudo column to generate a value from a sequence that would be used for a specified database column. E . If a sequence starting from a value 100 and incremented by 1 is used by more then one application, then all of these applications could have a value of 105 assigned to their column whose value is being generated by the sequence. F . You use REUSE clause when creating a sequence to restart the sequence once it generates the maximum value defined for the sequence.

A . It is possible for more than two threads to deadlock at once. B . The JVM implementation guarantees that multiple threads cannot enter into a deadlocked state. C . Deadlocked threads release once their sleep（） method’s sleep duration has expired. D . Deadlocking can occur only when the wait（）， notify（）， and notifyAll（） methods are used incorrectly. E . It is possible for a single-threaded application to deadlock if synchronized blocks are used incorrectly. F . If a piece of code is capable of deadlocking， you cannot eliminate the possibility ofdeadlocking by insertinginvocations of Thread.yield（）.

A . An autonomous wireless solution includes lightweight APs and WLAN controllers. The APs and the WLAN controllers are managed by a WLAN solution engine （WLSE/WLSM）. B . An autonomous wireless solution includes lightweight APs and WLAN controllers. The APs and the WLAN controllers are managed by the Cisco Wireless Control System （WCS）. C . A lightweight wireless solution includes lightweight APs and WLAN controllers. The APs and the WLAN controllers are managed by a WLAN solution engine （WLSE/WLSM）. D . A lightweight wireless solution consists of autonomous access points （APs）， which are managed by a WLAN solution engine （WLSE/WLSM）. E . A lightweight wireless solution includes lightweight APs and WLAN controllers. The APs and the WLAN controllers are managed by the Cisco Wireless Control System （WCS）.

A . A TACACS+ server is required to implement 802.1x. B . MIC protects against man-in-the-middle and replay attacks. C . The 802.1x standard provides encryption services for wireless clients. D . The AES （symmetric block cipher） is specified in the IEEE 802.11i specification. E . The IEEE 802.11i specification uses RC4 as its encryption mechanism. F . WPA requires TKIP and AES as encryption methods.

A . Passive routes are in the process of being calculated by DUAL. B . EIGRP supports VLSM，route summarization，and routing update authentication. C . EIGRP exchanges full routing table information with neighboring routers with every update. D . If the feasible successor has a higher advertised distance than the successor route，it becomes theprimary route. E . A query process is used to discover a replacement for a failed route if a feasible successor is not identified from the current routing information.

A .  Dense mode multicast requires explicit join messages from their members. B .  Dense mode multicast uses a push model to flood traffic throughout the network and then prunes the  unwanted traffic. C .  Sparse mode multicast uses a pull model to send multicast traffic to where it is requested.   D .  Sparse mode uses reverse path forwarding （RPF） to prune off redundant flows. E .  The primary use of sparse mode multicast is for test labs and router performance testing.

A . A subquery can retrieve zero or more rows  B . Only two subqueries can be placed atone level  C . A subquery can be used only in SQL query statements  D . A subquery can appear on either side of a comparison operator  E . There is no limit on the number of subquery levels in the WHERE clause of a SELECT statement&e

A .  b.equals（b） returns true. B .  b.equals（c） returns the same result as b == c. C .  b.eqials（c） can return false even if c.equals（b） returns true. D .  b.equals（c） throws an exception if b and c are different wrapper types. E .  b.equals（c） returns false if the type of wrapper objects being compared are different.

A . It is possible for more than two threads to deadlock at once. B . The JVM implementation guarantees that multiple threads cannot enter into a deadlocked state. C . Deadlocked threads release once their sleep() method's sleep duration has expired. D . Deadlocking can occur only when the wait(), notify(), and notifyAll() methods are used incorrectly. E . It is possible for a single-threaded application to deadlock if synchronized blocks are used incorrectly. F . If a piece of code is capable of deadlocking, you cannot eliminate the possibility of deadlocking by inserting invocations of Thread.yield().

A . It is possible to synchronize static methods. B . When a thread has yielded as a result of yield（）， it releases its locks. C . When a thread is sleeping as a result of sleep（）， it releases its locks. D . The Object.wait（） method can be invoked only from a synchronized context. E . The Thread.sleep（） method can be invoked only from a synchronized context. F . When the thread scheduler receives a notify（） request， and notifies a thread， that thread immediately releases its lock.

<img src='https://img2.soutiyun.com/ask/uploadfile/2019-03-27/900591de4611848eaa661230b23f7c01.jpg' /> <img src='https://img2.soutiyun.com/ask/uploadfile/2019-03-27/096a8f1a86972212e5c4d4c53f88ec71.jpg' /> A.The application will crash. B.The code on line 29 will be executed. C.The code on line 5 of class A will execute. D.The code on line 5 of class B will execute. E.The exception will be propagated back to line 27.