What ensures that voice packets are given priority throughout the network so that conversations arrive intact?（）A、CentrexB、Packet encryptionC、Intelligent call routingD、QoS

第1题：

Why is QoS important in a converged network?（）

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

第2题：

Refer to the exhibit. A router has a 256 kbps Frame Relay circuit connected to interface serial 0/0. As a large FTP packet is being placed into the hardware transmit queue of interface serial 0/0， a voice packet is placed into the priority queue of that interface. How， and in what order， wi the packets be transmitted？（）

• A、the voice packet will be transmitted first， followed by the FTP packet in its entirety
• B、the voice packet will be transmitted first， followed by the fragmented FTP packet
• C、the FTP packet will be fragmented and the voice packet will be interleaved
• D、the FTP packet will be transmitted first in its entirety， follow by the voice packet

第3题：

Which parameter， when enabled on a standalone access point， gives the highest priority to a voice packet even when qos is not enabled？（）

• A、igmp snooping
• B、wmm
• C、qos element for wireless phones
• D、avvid priority mapping

第4题：

Which statement is true about the Call Admission Control （CAC） feature in VoIP networks？（）

• A、 CAC is used to allocate enough bandwidth for the number of calls that are allowed on the VoIP network.
• B、 CAC is used to protect the quality of the voice calls by preventing call establishment if enough resources are not available on the network.
• C、 CAC provides queuing mechanisms for voice calls if the packets exceed the configured or budgeted rate.
• D、 In a VoIP network the CAC can be replaced with the LLQ QoS mechanism if it has been properly implemented.

第5题：

Which statement best describes the application of link fragmentation and interleaving （LFI）？（）

• A、It compresses the Layer 2 payload and marks the packet as a high priority to be transmitted first
• B、It fragments larger packets and allows VoIP packets to be transmitted in between them.
• C、It stops the transmission of large packets when priority packets arrive.
• D、It sends high priority packets in between normal traffic packets.

第6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7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8题：

Which two statements are true about network voice traffic？ （Choose two.）（）

• A、 Voice traffic is affected more by link speed than FTP traffic is.
• B、 Voice traffic is affected more by packet delays than FTP traffic is.
• C、 Voice streams involve larger packet sizes than most TCP network traffic involves.
• D、 Voice traffic is more sensitive to packet loss than TCP network traffic is.
• E、 Voice traffic requires QOS mechanisms only in heavily loaded network segments.

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第13题：

Which two statements about the QoS policy generation phase of the Cisco SDM QoS wizard are true？ （）

• A、 The SDM QoS wizard will create two real-time traffic classes to handle VoIP and voice signaling packets.
• B、 The SDM QoS wizard will create three real-time traffic classes to handle VoIP， voice signaling， and video packets.
• C、 The SDM QoS wizard will create four real-time traffic classes to handle VoIP， voice signaling， video， and video streaming packets.
• D、 The SDM QoS wizard will create two business-critical traffic classes to handle transactional and network management packets.
• E、 The SDM QoS wizard will create three business-critical traffic classes to handle transactional， network management， and routing packets.
• F、 The SDM QoS wizard will create four business-critical traffic classes to handle transactional， network management， routing， and best-effort packets.

第14题：

What is a benefit of Internet protocol (IP) telephony?（）

• A、Synchronizes password exchanges for call setup
• B、Eliminates the need for physical cabling in a TCP/IP network
• C、Enables two-way voice transmission over a packet-switched TCP/IP network
• D、Creates an encrypted tunnel for voice through a Transmission Control Protocol (TCP)/IP network

第15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16题：

What is the goal of QoS in a network？ （）

• A、prevent packets from being dropped
• B、increase available bandwidth
• C、reduce hardware errors
• D、provide predictable network service
• E、eliminate propagation delay
• F、eliminate jitter and packet loss

第17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18题：

SDM creates a low latency queuing （LLQ） service policy with its associated classes. What are the two types of low latency queuing available using the SDM QoS wizard？（）

• A、 FIFO queuing， which provides a means to hold packets while they are waiting to exit an interface
• B、 Priority queuing， which ensures a fixed amount of bandwidth
• C、 Custom queuing （CQ）， which provides a queuing tool that services all queues， even during times of congestion
• D、 Bandwidth queuing， which ensures a minimum amount of bandwidth
• E、 Weighted fair queuing （WFQ）， which classifies packets based on flows

第19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20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

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