单选题Why is QoS important in a converged network?（）A Because data does not need to arrive intact, so data transfer rates can be variableB Because lost voice-data packets must be retransmittedC Because voice data packets should arrive quickly and sequentiall

第1题：

Which two statements are true about Voice over IP （VoIP） packet delivery in a digital infrastructure？ （）

• A、 Packets can arrive out of order.
• B、 Packets must take the same path to the destination.
• C、 Once packets are received at the destination router， the router performs sampling to ensure the quality of the voice traffic.
• D、 Packets can experience varying delays across the network.
• E、 Packets containing voice samples are sequentially numbered by default， allowing for reordering upon arrival at the terminal router along the path.

第2题：

VOIP has been implemented at the main office of the Company network. Which two statements  are true about voice packets in a LAN？（）

• A、 Voice carrier stream utilizes Real-Time Transport Protocol (RTP) to carry the audio/media  portion of the VoIP communication.  
• B、 Voice traffic data flow involves large volumes of large packets.  
• C、 Because a packet loss involves a small amount of data, voice traffic is less affected by packet  losses than traditional data traffic is.  
• D、 Voice packets are encapsulated in TCP segments to allow for proper sequencing during  delivery. 
• E、 Voice packets are very sensitive to delay and jitter. 

第3题：

Which three practices are important to the implementation of a DiffServ QoS architecture？（）

• A、 Because services are allocated throughout the network before the transmission of data begins， traffic classes can be guaranteed QoS services.
• B、 Traffic classes are marked with Layer 2 markings to allow for more granularity in identifying traffic classes.
• C、 Traffic classes are marked with Layer 3 markings to allow them to traverse different network types without loss of QoS information.
• D、 Traffic classes allow networks to provide proper QoS treatment of packets without applications having to request services.
• E、 Based upon the network capabilities， QoS markings are placed on packets as needed throughout the network to allow for proper QoS treatment of packets.
• F、 QoS markings are placed on packets as close to the network edge as possible to allow distribution and core devices to determine QoS actions as quickly as possible.

第4题：

What are two major sources of delay that can be managed by QoS in voice-enabled networks？（）

• A、propagation delay
• B、voice packet serialization delay
• C、congested egress queues
• D、header overhead
• E、packets dropped because of CRC errors

第5题：

Authentication for user data traffic is important, but so is authentication for IP voice traffic. The Cisco 830 802.1 feature provides an easier method for allowing IP voice traffic through the VPN, because it（）.

• A、requires access lists to identify the voice traffic 
• B、can allow traffic from a device without 802.1X authentication, by MAC address
• C、can allow traffic from Cisco IP phones by listening to their CDP advertisements
• D、allows all packets marked with a ToS of 5 to bypass authentication
• E、allows all IP voice packets to bypass authentication via stateful inspection

第6题：

A data file become corrupted in your database due to bad sectors on the disk. Because of corruption， you lost all the important tables in that data file. Which method would you use for recovery？（）

• A、 Flash back all the tables in the data file， one by one.
• B、 Restore the data file to a new location and perform a media recovery.
• C、 Flash back the database， there is no need to restore the data file.
• D、 Restore the data file from the most recent backup and flash the database.

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第13题：

A data file became corrupted in your database due to bad sectors on the disk. Because of corruption， you lost all the important tables in that data file. Which method would you use for recovery？（）

• A、flash back all the tables in the data file， one by one
• B、restore the data file to a new location and perform a media recovery
• C、flash back the database; there is no need to restore the data file
• D、restore the data file from the most recent backup and flash back the database

第14题：

When troubleshooting a network， the output of the command show interfaces indicates a large number of runts. What is a runt？（）

• A、the number of packets that are discarded because they exceed the maximum packet size of the medium
• B、errors created when the CRC generated by the originating LAN station or far-end device does not match the checksum calculated from the data received.
• C、the number of packets that are discarded because they are smaller than the minimum packet size of the medium
• D、the number of received packets that were ignored by the interface because the interface hardware ran low on internal buffers
• E、the number of times that the interface requested another interface within the router to slow down

第15题：

Why is QoS important in a converged network?（）

• A、Because data does not need to arrive intact, so data transfer rates can be variable
• B、Because lost voice-data packets must be retransmitted
• C、Because voice data packets should arrive quickly and sequentially, and with no lost data
• D、Because voice data packets must follow a single dedicated path through the network

第16题：

What ensures that voice packets are given priority throughout the network so that conversations arrive intact?（）

• A、QoS
• B、Centrex
• C、Packet encryption
• D、Intelligent call routing

第17题：

In your production database, users report that they are unable to generate reports on an important table because it does not contain any data. While investigating the reason, you realize that another user executed the TRUNCATE TABLE command, which accidentally caused the data to be lost. Now you want to recover the lost data of the table without affecting objects in other schemas. Which method must you use to recover the lost data?（）

• A、Complete Recovery with online redo log
• B、Complete Recovery with archived redo log
• C、Tablespace Point-in-Time Recovery (TSPITR)
• D、Incomplete Recovery with system change number (SCN)

第18题：

The user SCOTT executes the following command successfully to increase the salary values in one of his sessions：  SQL> UPDATE emp SET sal=sal*1.15 WHERE deptno=20；  Before SCOTT ends the transaction， user HR who has the privileges on EMP table executes a query to fetch the salary details but finds the old salary values instead of the increased values. Why does HR still see the old data？（）

• A、because of redo data from redo log file
• B、because of data from database buffer cache
• C、because of data from a temporary tablespace
• D、because of undo data from the undo tablespace

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