ActualTests.Cisco.640-802.Exam.Q.and.A.08.15.08-DDU (1130589), страница 3
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Examples include: TCP, UDP, and SPX.QUESTION 22:Which OSI layer header contains the address of a destination host that is on anothernetwork?Actualtests.com - The Power of Knowing640-802A. ApplicationB. PresentationC. SessionD. TransportE. NetworkF. Data linkG. PhysicalAnswer: EExplanation:Only network address contains this information. To transmit the packets the sender usesnetwork address and datalink address. But the layer 2 address represents just the addressof the next hop device on the way to the sender. It is changed on each hop.
Networkaddress remains the same.QUESTION 23:Which of the following correctly describe steps in the OSI data encapsulationprocess? (Choose two)A. The presentation layer translates bits into voltages for transmission across the physicallink.B. The transport layer divides a data stream into segments and adds reliability and flowcontrol information.C. Packets are created when the network layer adds Layer 3 addresses and controlinformation to a segment.D. The data link layer adds physical source and destination addresses and an FCS to thesegment.E. Packets are created when the network layer encapsulates a frame with source anddestination host addresses and protocol-related control information.Answer: B, CExplanation:The Transport Layer:You can think of the transport layer of the OSI model as a boundary between the upperand lower protocols.
The transport layer provides a data transport service that shields theupper layers from transport implementation issues such as the reliability of a connection.The transport layer provides mechanisms for:Segmenting upper layer applicationThe establishment, maintenance, and orderly termination of virtual circuitsinformation flow control and reliability via TCPTransport fault detection and recoveryThe Network Layer:Actualtests.com - The Power of Knowing640-802Layer three of the OSI model is the network layer.The network layer creates and sends packets from source network to destinationnetwork.it provides consistent end-to-end packet delivery service and control informationit creates and uses layer3 addresses for use in path determination and to forwardpackets.Incorrect Answers:A: This correctly describes the physical layer, not the presentation layer.D: Although the data link layer adds physical (MAC) source and destination addresses, itadds it to a frame, not a segment.E: Packets are encapsulated, not frames.QUESTION 24:When files are transferred between a host and an FTP server, the data is dividedinto smaller pieces for transmission.
As these pieces arrive at the destination host,they must be reassembled to reconstruct the original file. What provides for thereassembly of these pieces into the correct order?A. The sequence number in the TCP headerB. The Start Frame Delimiter in the 802.3 PreambleC.
The TTL in the IP headerD. The acknowledgement number in the segment headerE. The frame check sequence in the Ethernet frame trailerAnswer: AExplanation:The Transport layer can provide reliable networking via acknowledgments, sequencing,and flow control.Acknowledgments Delivered segments are acknowledged to the sender. If they are notacknowledged, the sender will retransmit.Sequencing Data segments are sequenced into their original order when they arrive at thedestination.Flow Control Provides buffer controls that prevent packet flooding to the destinationhost.
Buffers store bursts of data for processing when the transmission is complete.Layer 4 protocols include the following:Transmission Control Protocol (TCP)User Datagram Protocol (UDP)Sequenced Packet Exchange (SPX)A reliable communications protocol created byNovell NetWareQUESTION 25:Actualtests.com - The Power of Knowing640-802DRAG DROPYou work as a network administrator at Certkiller .com.Your boss, Mrs.
Certkiller, is interested in the OSI layers. Match the terms with theappropriate layer. Some options are not used.Answer:Explanation:The Transport layer segments and reassembles data into a data stream. Services locatedin the Transport layer segment and reassemble data from upper-layer applications andunite it into the same data stream. They provide end-to-end data transport services andcan establish a logical connection between the sending host and destination host on aninternetwork.TCP and UDP transport protocol lies on Transport Layer, which break down the datacoming from upper layer into segment.Windows are used to control the amount of outstanding, unacknowledgeddata segments that is also on Transport Layer.Network Layer:The Network layer (also called layer 3) manages device addressing, tracks the location ofActualtests.com - The Power of Knowing640-802devices on the network, and determines the best way to move data, which means that theNetwork layer must transport traffic between devices that aren't locally attached.
Routers(layer 3 devices) are specified at the Network layer and provide the routing serviceswithin an internetwork.Protocol Data Packets (PDU) on Network Layer is known as Packets. Routing andRouted protocols are lies on Network Layer.Routing Protocol: RIP, IGRP, EIGRP, OSPF, BGPRouted Protocol: IP, IPXQUESTION 26:Refer to the following exhibit:What data structure is described in the exhibit shown above?A.
IP datagramB. TCP segmentC. Ethernet frameD. UDP datagramE. FDDI frameF. Token Ring frameG. None of the aboveAnswer: BExplanation:The Figure below illustrates the fields and overall format of a TCP packet.Twelve fields comprise a TCP packet.Actualtests.com - The Power of Knowing640-802The following descriptions summarize the TCP packet fields illustrated above.1. SourcePort and DestinationPort-Identifies points at which upper-layer source anddestination processes receive TCP services.2.3.
Sequence Number-Usually specifies the number assigned to the first byte of data in thecurrent message. In the connection-establishment phase, this field also can be used toidentify an initial sequence number to be used in an upcoming transmission.4.5. Acknowledgment Number-Contains the sequence number of the next byte of data thesender of the packet expects to receive.6.7. Data Offset-Indicates the number of 32-bit words in the TCP header.8.9. Reserved-Remains reserved for future use.10.11.
Flags-Carries avariety of control information, including the SYN and ACK bits used for connectionestablishment, and the FIN bit used for connection termination.12.13. Window-Specifies the size of the sender's receive window (that is, the buffer spaceavailable for incoming data).14.15. Checksum-Indicates whether the header was damaged in transit.16.17. Urgent Pointer-Points to the first urgent data byte in the packet.18.19. Options-Specifies various TCP options.Data-Contains upper-layer information.QUESTION 27:Network equipment supporting the use of flow control mechanisms has beenActualtests.com - The Power of Knowing640-802recently installed in the Certkiller network.
What is the purpose of flow control in adata network?A. It ensures that data is retransmitted if an acknowledgment is not received.B. It reassembles segments in the correct order on the destination device.C. It provides a mechanism for the receiver to control the transmission speed.D. It regulates the size of each datagram segment.E. All of the above are functions of flow controlAnswer: CExplanation:Flow control paces the transmission of data between a sending device and a receivingdevice.
Flow control ensures that the receiving device can absorb the data sent to itbefore the sending device sends more. When the buffers on the receiving device are full,a message is sent to the sending device to suspend transmission until the data in thebuffers has been processed.Incorrect Answers:A. Data retransmission mechanisms are not handled by control. They are most oftenhandled by transport layer protocols such as TCP.B. This describes the reassembly portion of the segmentation and reassembly (SAR)function of network equipment.D. The maximum transmission unit (MTU) handles the regulation of maximum framesizes.QUESTION 28:Part of the Certkiller network is displayed below:Study the exhibit shown above. Host Certkiller A has established a connection withthe Certkiller II server attached to interface E0 of the Certkiller 2 router.
Which ofthe following statements describe the information contained in protocol data unitssent from Host Certkiller to Certkiller II? (Choose three)Actualtests.com - The Power of Knowing640-802A. The destination port number in a segment header will have a value of 80B.
The destination IP address of a packet will be the IP address of the E0 interface of theCertkiller 1 routerC. The destination IP address of a packet will be the IP address of the network interfaceof the Certkiller II serverD. The destination address of a frame will be the MAC address of the E0 interface ofCertkiller 1 routerAnswer: A, C, DQUESTION 29:You have just installed a new web server on the Certkiller network.
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