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川大软院计网选择题答案

川大软院计网选择题答案

川大软院计网选择题答案C h a p t e r4(含答案)(总5页)--本页仅作为文档封面，使用时请直接删除即可----内页可以根据需求调整合适字体及大小--CHAPTER 4: NETWORK LAYERof the following groups belongs to network layer protocol_____D____, TCP andUDP, IP, and UDP, IMAP andIP, BGP, and RIP3-PDU is named as ____C_____a datagram network, the forwarding decision is based on the valueof the ____B field in the packet header.addressaddressof the choices areblocking happens on ____A_____portportfabricsof aboveno free buffers in router, the arriving packets will be: Anormal IP packet forwarding at a router, which of the following packet fields are updated____C____IPaddressIP addressport numberof the following IP address doesn’t belong to the network______D___are given an IP network of and told that you need to separate this network into sub networks that can support a maximum of 30 hosts per subnet. This will help alleviate congestion on thenetwork. What subnet mask can you use to create the subnetsnecessary to meet the given criteria___C______IP datagram of 1500 bytes (20 byte of IP header plus 1480 bytes of IP payload) arrives at a router and must be forwarded to a link with an MTU of 500 bytes. Thus the router has to fragment the datagram. To the last fragment, the value of offset should be _____D____is a ____C_____ protocol.unreliablereliableunreliablereliableICMP message type is the basis for the Traceroute utility?B RequestexpiredUnreachableReassembly Time Exceedin the path are not allowed to _________________B__________.the packet they receivesource or destination addressthe packetof the choices are correctallows a site to use a set of private addresses for internal communication and a set of global Internet addresses forcommunication with the rest of the world.of the choices are correctmany bits are there in IPv6______C___CIDR notation, which of the following networks contains host is the limited broadcast address corresponding to the nodewith the following IP address: of the aboveclassful IP addressing, how many network bits does have?Ais the broadcast IP address for / 26Da networkFrom IP address perspective they can physically reach each other without intervening router and the device interfaces with: C IP addressTCP port #network part of IP addresshost part of IP addressInternet’s network layer has three major components, the first component is the IP protocol, the second component is therouting protocol, the final componenttranslationaddressing assigns an address to the network address for this network （）are two 16-bit integers: 1110 0110 0110 0110, 1101 0101 0101 0101.Their checksum isA____.use of hierarchy in routing tables can __A______ the size of the routing tables.reduce nor increaseof the choices are correctof the following protocol doesn’t belong to intra-AS routing protocol_____B____of the following protocol belongs to intra-AS routing protocol ______A___(DistanceVector)(Link State)OSPF network, a ____B_____ belongs to both an area and the backbone.routerborder routerrouterrouteris an inter-domain routing protocol using path vector routing.of the choices are correctuses the services of ___C____.of the choices are correctRouting Information Protocol (RIP) is an intra-domain routing based on _______A__ routing.vectorstatevectorof the aboveof the following algorithm has the so called count-to-infinity problem?Calgorithmalgorithmvector algorithmof the above。

四川大学06-07计算机网络考试试题答案

四川大学06-07计算机网络考试试题答案

四川大学期末考试试题参考答案（2006-2007学年第1学期）课程号：30410340 课序号：课程名称：计算机网络（A卷）任课教师：吕光宏.徐林.张靖宇-付静涛适用专业年级：计算机2004级学生人数：印题份数：学号：姓名：1、Translation (10 Score)RTT：往返时间CSMA/CD：载波侦听/冲突发现URL：统一资源定位器(符)RIP：选路信息协议A TM：异步传输模式TDM：时分多路复用PPP：点对点传输协议IMAP：因特网消息访问协议ICMP：网际控制报文协议Multicast：组播2、Choice (20 Score)3、True or False? why? (15 Score)(1)（╳）改：每个分组都是独立的，不会沿着相同的路径传输。

(2)（╳）改：使用UDP(3)（√）(4)（╳）改：等待一个随机时间才能发送，如果等待相同的时间就会再次发生冲突。

(5)（╳）改：收到的是4个应答4、Question (25 Score)(1)答：a. 扩充的地址容量：IP从32比特增加到128比特（1）引入了任意点传送地址。

（1）b. 改进的40字节报头。

（2）c. 引入“流”标注和优先权(1)(2)答：MAC地址是固化在网卡上的物理地址。

(1)IP地址是网络层的地址。

（1）域名是为了便于记忆IP地址而提出的助记符号。

（1）域名需要转换成IP地址以后才能在网络中传输。

（1）IP地址到局域网传输需要MAC地址。

（1）(3)(4) Token Ring的操作过程？答：（1）首先进行环的初始化，产生一个空令牌，在环上流动；（2）希望发送帧的站必须等待，直到检测到下一个空令牌的到来；（3）想发送站拿到空令牌后，首先将令牌状态置忙且在忙令牌的后面发一个数据帧；（4）当令牌忙时，环上无空令版，所有想发送的站必须等待；（5）数据沿环经过每个站，都将该帧的目的地址与本地址比较，地址相符，则将该帧接收，帧将继续在环上流动，若地址不符则将该帧转发至下一站；（6）发送帧沿环流动一周回到发送站，由发送站移去并释放令牌。

2023年四川省德阳市全国计算机等级考试网络技术真题(含答案)

2023年四川省德阳市全国计算机等级考试网络技术真题(含答案)

2023年四川省德阳市全国计算机等级考试网络技术真题(含答案)学校:________ 班级:________ 姓名:________ 考号:________一、单选题(10题)1.计算机种类繁多，按照“现实的分类”，可以将计算机分为( )。

A.台式机、便携机、掌上机3种类型B.巨型机、大型机、中型机、小型机和微型机5种类型C.服务器、工作站、台式机、便携机、手持设备5种类型D.大型主机、小型计算机、个人计算机、工作站、巨型计算机和小巨型机6种类型2.下列关于RPR技术的描述中，错误的是()。

A.RPR与FDDI一样使用双环结构B.在RPR环中，源节点向目的节点成功发出的数据帧要由目的节点从环中收回C.RPR环中每一个节点都执行MPLS公平算法D.RPR环能够在50ms内实现自愈3.下列关于xDSL技术的描述中，错误的是（）。

A.xDSL技术按上行与下行速率分为速率对称与非对称两类B.ADSL技术在现有用户电话线上同时支持电话业务和数字业务C.ADSL上行传输速率最大可以达到8MbpsD.HDSL上行传输速率为1．544Mbps4.下列关于Serv-U FTP服务器配置的描述中，正确的是（）。

A.用户可在服务器中自行注册新用户B.配置服务器域名时，必须使用该服务器的域名C.配置服务器的IP地址时，服务器若有多个IP地址需分别添加D.添加名为“anonymous”的用户时，系统会自动判定为匿名用户5.6.时移电视和直播电视的基本原理相同，主要差别在于传输方式的差异.时移电视是采用什么来为用户实现时移电视的功能?( )A.组播方式B.广播方式C.点播方式D.多播方式7.当今IT的发展与安全投入，安全意识和安全手段之间形成()。

A.安全风险屏障B.安全风险缺口C.管理方式的变革D.管理方式的缺口8.下列软件中不能用于网络嗅探的是（）。

A.SnifferB.TCPdumpC.WiresharkD.OPNET9.以下哪一个不是搜索引擎中使用的运算符()。

川大软院计网选择题答案Chapter4(含答案)

川大软院计网选择题答案Chapter4(含答案)

CHAPTER 4: NETWORK LAYER1.Which of the following groups belongs to network layer protocol? _____D____A.IP, TCP and UDPB.ARP, IP, and UDPC.FTP, IMAP and IPD.ICMP, BGP, and RIP2.The 3-PDU is named as ____C_____A.messageB.packetC.datagramD.segment3.In a datagram network, the forwarding decision is based on the value of the____B field in the packet header.A.source addressB.destination addressbelD.None of the choices are4.HOL blocking happens on ____A_____A.input portB.output portC.switching fabricsD.all of above5.If no free buffers in router, the arriving packets will be: AA.droppedB.queuedC.returnedD.marked6.During normal IP packet forwarding at a router, which of the following packetfields are updated? ____C____A.Source IP addressB.Destination IP addressC.ChecksumD.Destination port number7.Which of the following IP address doesn’t belong to the 202.115.32.0/25 network?______D___A.202.115.32.1B.202.115.32.11C.202.115.32.120D.202.115.32.1298.You are given an IP network of 192.168.5.0 and told that you need to separatethis network into sub networks that can support a maximum of 30 hosts per subnet.This will help alleviate congestion on the network. What subnet mask can you use to create the subnets necessary to meet the given criteria? ___C______A.255.255.255.0B.255.255.255.128C.255.255.255.224D.255.255.255.2409.An IP datagram of 1500 bytes (20 byte of IP header plus 1480 bytes of IP payload)arrives at a router and must be forwarded to a link with an MTU of 500 bytes.Thus the router has to fragment the datagram. To the last fragment, the value of offset should be _____D____A.1440B.1000C.186D.18010.IP is a ____C_____ protocol.A.connection-oriented unreliableB.connection-oriented reliableC.connectionless unreliableD.connectionless reliable11.Which ICMP message type is the basis for the Traceroute utility?BA.Echo RequestB.TTL expiredC.Host UnreachableD.Fragment Reassembly Time Exceed12.Routers in the path are not allowed to _________________B__________.A.fragment the packet they receiveB.change source or destination addressC.decapsulate the packetD.All of the choices are correct13.____B_____ allows a site to use a set of private addresses for internalcommunication and a set of global Internet addresses for communication with the rest of the world.A.DHCPB.NATC.ICMPD.None of the choices are correct14.How many bits are there in IPv6 ? ______C___A.32B.64C.128D.25615.In CIDR notation, which of the following networks contains host 192.168.14.2?CA.192.168.10.0/22B.192.168.11.0/21C.192.168.12.0/23D.192.168.13.0/2416.What is the limited broadcast address corresponding to the node with thefollowing IP address: 131.15.46.59?DA.131.15.46.255B.131.15.255.255C.255.255.255.255D.None of the above17.In classful IP addressing, how many network bits does 125.140.128.16 have?AA.8B.16C.24D.3218.What is the broadcast IP address for 193.140.141.128 / 26 ?DA.193.140.141.128B.193.140.141.127C.255.255.255.63D.193.140.141.19119.What’s a network? From IP address perspective they can physically reach eachother without intervening router and the device interfaces with: CA.same IP addressB.same TCP port #C.same network part of IP addressD.same host part of IP address20.The Internet’s network layer has three major components, the first component isthe IP protocol, the second component is the routing protocol, the final component is____.DA.forwardingB.address translationC.checkD.ICMP21.IP addressing assigns an address to 223.10.198.250/29, the network address forthis network is____.A（）A.223.10.198.248B.223.10.198.250C.223.10.198.0D.223.10.0.022.There are two 16-bit integers: 1110 0110 0110 0110, 1101 0101 0101 0101. Theirchecksum isA____.A.0100010001000011B.1011101110111100C.1111111111111111D.100000000000000023.The use of hierarchy in routing tables can __A______ the size of the routingtables.A.reduceB.increaseC.neither reduce nor increaseD.None of the choices are correct24.Which of the following protocol doesn’t belong to intra-AS routing protocol?_____B____A.RIPB.BGPC.OSPFD.IRAP25.Which of the following protocol belongs to intra-AS routing protocol?______A___A.RIPB.BGPC.DV (Distance Vector)D.LS (Link State)26.In OSPF network, a ____B_____ belongs to both an area and the backbone.A.internal routerB.area border routerC.boundary routerD.backbone router27._A___ is an inter-domain routing protocol using path vector routing.A.BGPB.RIPC.OSPFD.None of the choices are correct28.RIP uses the services of ___C____.A.TCPB.IPC.UDPD.None of the choices are correct29.The Routing Information Protocol (RIP) is an intra-domain routing based on_______A__ routing.A.distance vectorB.link stateC.path vectorD.all of the above30.Which of the following algorithm has the so called count-to-infinity problem?CA.Flooding algorithmB.Link-state algorithmC.Distance vector algorithmD.None of the above。

(完整版)川大软院计网选择题答案Chapter1(含答案)

(完整版)川大软院计网选择题答案Chapter1(含答案)

1.1 In the following options, which does not define in protocol? ( D )A the format of messages exchanged between two or more communicatingentitiesB the order of messages exchanged between two or more communicating entitiesC the actions taken on the transmission of a message or other eventD the transmission signals are digital signals or analog signals1.2 In the following options, which is defined in protocol? ( A )A the actions taken on the transmission and/or receipt of a message or other eventB the objects exchanged between communicating entitiesC the content in the exchanged messagesD the location of the hosts1.3 An application can rely on the connection to deliver all of its data without error and in the proper order. The sentence describes (C ).A flow controlB congestion-controlC reliable data transferD connection-oriented service1.4 The Internet’s connection-oriented service has a name, it is ( A ).A TCPB UDPC TCP/IPD IP1.5 The Internet’s connectionless service is called ( B ).A TCPB UDPC TCP/IPD IP1.6 Which of the following nodes belongs to the network core?CA. a Web ServerB. a Host with Win2003 ServerC. a Router with NAT serviceD. a Supernode on Skype Network1.7 In the Internet, the equivalent concept to end systems is ( )A.A hostsB serversC clientsD routers1.8 In the Internet, end systems are connected together by ( C ).A copper wireB coaxial cableC communication linksD fiber optics1.9 End systems access to the Internet through its (C ).A modemsB protocolsC ISPD sockets1.10 In the following options, which belongs to the network core? ( B )A end systemsB routersC clientsD servers1.11 End systems, packet switches, and other pieces of the Internet, run ( D ) that control the sending and receiving of information within the Internet.A programsB processesC applicationsD protocols1.12 The internet allows ( D ) running on its end systems to exchange data with each other.A clients applicationsB server applicationsC P2P applicationsD distributed applications1.13 The protocols of various layers are called ( A ).A the protocol stackB TCP/IPC ISPD network protocol1.14 In the OSI reference model, the upper layers of the OSI model are, in correct orderDA Session, application, presentationB Session, presentation, applicationC Session, application, presentation, physicalD Application, presentation, session1.15 The lower layers of the OSI model are, in correct orderDA physical, system, network, logicalB physical, logical, network, systemC physical, transport, network, data linkD physical, data link, network, transport1.16 The Internet Protocol (IP) generally corresponds to which OSI layer?AA Network (layer three)B Transport (layer four)C Data link (layer two)D Session (layer five)1.17 What layer of the OSI model is designed to perform error detection functions?BA PhysicalB Data linkC NetworkD transport1.18 Which of the following protocol layers is not explicitly part of the Internet Protocol Stack? _____B____A. application layerB. session layerC. data link layerD. transport layer1.19 The 5-PDU is called__A_A. messageB. segmentC. datagramD. frame1.20 The Internet’s network layer is responsible for moving network-layer packets known as B( ) from one host to another.A frameB datagramC segmentD message1.21 Transport-layer packets are called:BA. messageB. segmentC. datagramD. frame1.22 The units of data exchanged by a link-layer protocol are called ( A).A FramesB SegmentsC DatagramsD bit streams1.23 There are two fundamental approaches to building a network core, ( B ) and packet switching.A electrical current switchingB circuit switchingC data switchingD message switching1.24 Datagram networks and virtual-circuit networks differ in that ( C ).A datagram networks are circuit-switched networks, and virtual-circuit networksare packet-switched networks.B datagram networks are packet-switched networks, and virtual-circuit networksare circuit-switched networks.C datagram networks use destination addresses and virtual-circuit networks useVC. numbers to forward packets toward their destination.D datagram networks use VC. numbers and virtual-circuit networks usedestination addresses to forward packets toward their destination.1.25 (A ) means that the switch must receive the entire packet before it can begin to transmit the first bit of the packet onto the outbound link.A Store-and-forward transmissionB FDMC End-to-end connectionD TDM1.26 In ( C ) networks, the resources needed along a path to provide for communication between the end system are reserved for the duration of the communication session.A packet-switchedB data-switchedC circuit-switchedD message-switched1.27 In ( A ) networks, the resources are not reserved; a session’s messages use the resources on demand, and as a consequence, may have to wait for access to communication link.A packet-switchedB data-switchedC circuit-switchedD message-switched1.28 In a circuit-switched network, if each link has n circuits, for each link used by the end-to-end connection, the connection gets ( A) of the link’s bandwidth for the duration of the connection.A a fraction 1/nB allC 1/2D n times1.29 For (C ), the transmission rate of a circuit is equal to the frame rate multiplied by the number of bits in a slot.A CDMAB packet-switched networkC TDMD FDM1.30 The network that forwards packets according to host destination addresses is called ( D) network.A circuit-switchedB packet-switchedC virtual-circuitD datagram1.31 The network that forwards packets according to virtual-circuit numbers is called ( C ) network.A circuit-switchedB packet-switchedC virtual-circuitD datagram1.32 The time required to propagate from the beginning of the link to the next router is ( C).A queuing delayB processing delayC propagation delayD transmission delay1.33 Processing delay does not include the time to (B ).A examine the packet’s headerB wait to transmit the packet onto the linkC determine where to direct the packetD check bit-error in the packet1.34 In the following four descriptions, which one is correct? ( C)A The traffic intensity must be greater than 1.B The fraction of lost packets increases as the traffic intensity decreases.C If the traffic intensity is close to zero, the average queuing delay will be closeto zero.D If the traffic intensity is close to one, the average queuing delay will be closeto one.1.35 Suppose, a is the average rate at which packets arrive at the queue, R is the transmission rate, and all packets consist of L bits, then the traffic intensity is ( B ),A LR／aB La／RC Ra／LD LR／a1.36 Suppose there is exactly one packet switch between a sending host and a receiving host. The transmission rates between the sending host and the switch and between the switch and the receiving host are R1 and R2, respectively. Assuming that the switch uses store-and-forward packet switching, what is the total end-to-end delay to send a packet of length L? (Ignore queuing delay, propagation delay, and processing delay.) ( A )A L/R1＋L/R2B L/R1C L/R2D none of the above1.37 We are sending a 30 Mbit MP3 file from a source host to a destination host. Suppose there is only one link between source and destination and the link has a transmission rate of 10 Mbps. Assume that the propagation speed is 2 * 108 meters/sec, and the distance between source and destination is 10,000 km. Also suppose that message switching is used, with the message consisting of the entire MP3 file. How many bits will the source have transmitted when the first bit arrives at the destination?CA. 1 bitB. 30,000,000 bitsC. 500,000 bitsD. none of the above1.38 In the following entries, which is not a kind of access network?(D )A residential accessB company accessC wireless accessD local access1.39 The following technologies may be used for residential access, exceptDA. HFCB. DSLC. Dial-up modemD. FDDI1.40 Which kind of media is not a guided media? ( D)A twisted-pair copper wireB a coaxial cableC fiber opticsD digital satellite channel。

川大软院计网选择题答案Chapter1(含答案)

川大软院计网选择题答案Chapter1(含答案)

1.1 In the following options, which does not define in protocol? ( D )A the format of messages exchanged between two or more communicatingentitiesB the order of messages exchanged between two or more communicatingentitiesC the actions taken on the transmission of a message or other eventD the transmission signals are digital signals or analog signals1.2 In the following options, which is defined in protocol? ( A )A the actions taken on the transmission and/or receipt of a message or othereventB the objects exchanged between communicating entitiesC the content in the exchanged messagesD the location of the hosts1.3 An application can rely on the connection to deliver all of its data without error and in the proper order. The sentence describes (C ).A flow controlB congestion-controlC reliable data transferD connection-oriented service1.4 The Internet’s connection-oriented service has a name, it is ( A ).A TCPB UDPC TCP/IPD IP1.5 The Internet’s connectionless service is called ( B ).A TCPB UDPC TCP/IPD IP1.6 Which of the following nodes belongs to the network core?CA. a Web ServerB. a Host with Win2003 ServerC. a Router with NAT serviceD. a Supernode on Skype Network1.7 In the Internet, the equivalent concept to end systems is ( )A.A hostsB serversC clientsD routers1.8 In the Internet, end systems are connected together by ( C ).A copper wireB coaxial cableC communication linksD fiber optics1.9 End systems access to the Internet through its (C ).A modemsB protocolsC ISPD sockets1.10 In the following options, which belongs to the network core? ( B )A end systemsB routersC clientsD servers1.11 End systems, packet switches, and other pieces of the Internet, run ( D ) that control the sending and receiving of information within the Internet.A programsB processesC applicationsD protocols1.12 The internet allows ( D ) running on its end systems to exchange data with each other.A clients applicationsB server applicationsC P2P applicationsD distributed applications1.13 The protocols of various layers are called ( A ).A the protocol stackB TCP/IPC ISPD network protocol1.14 In the OSI reference model, the upper layers of the OSI model are, in correct orderDA Session, application, presentationB Session, presentation, applicationC Session, application, presentation, physicalD Application, presentation, session1.15 The lower layers of the OSI model are, in correct orderDA physical, system, network, logicalB physical, logical, network, systemC physical, transport, network, data linkD physical, data link, network, transport1.16 The Internet Protocol (IP) generally corresponds to which OSI layer?AA Network (layer three)B Transport (layer four)C Data link (layer two)D Session (layer five)1.17 What layer of the OSI model is designed to perform error detection functions?BA PhysicalB Data linkC NetworkD transport1.18 Which of the following protocol layers is not explicitly part of the Internet Protocol Stack? _____B____A. application layerB. session layerC. data link layerD. transport layer1.19 The 5-PDU is called__A_A. messageB. segmentC. datagramD. frame1.20 The Internet’s network layer is responsible for moving network-layer packets known as B( ) from one host to another.A frameB datagramC segmentD message1.21 Transport-layer packets are called:BA. messageB. segmentC. datagramD. frame1.22 The units of data exchanged by a link-layer protocol are called ( A).A FramesB SegmentsC DatagramsD bit streams1.23 There are two fundamental approaches to building a network core, ( B ) and packet switching.A electrical current switchingB circuit switchingC data switchingD message switching1.24 Datagram networks and virtual-circuit networks differ in that ( C ).A datagram networks are circuit-switched networks, and virtual-circuitnetworks are packet-switched networks.B datagram networks are packet-switched networks, and virtual-circuitnetworks are circuit-switched networks.C datagram networks use destination addresses and virtual-circuit networks useVC. numbers to forward packets toward their destination.D datagram networks use VC. numbers and virtual-circuit networks usedestination addresses to forward packets toward their destination.1.25 (A ) means that the switch must receive the entire packet before it can begin to transmit the first bit of the packet onto the outbound link.A Store-and-forward transmissionB FDMC End-to-end connectionD TDM1.26 In ( C ) networks, the resources needed along a path to provide for communication between the end system are reserved for the duration of the communication session.A packet-switchedB data-switchedC circuit-switchedD message-switched1.27 In ( A ) networks, the resources are not reserved; a session’s messages use the resources on demand, and as a consequence, may have to wait for access to communication link.A packet-switchedB data-switchedC circuit-switchedD message-switched1.28 In a circuit-switched network, if each link has n circuits, for each link used by the end-to-end connection, the connection gets ( A) of the link’s bandwidth for the duration of the connection.A a fraction 1/nB allC 1/2D n times1.29 For (C ), the transmission rate of a circuit is equal to the frame rate multiplied by the number of bits in a slot.A CDMAB packet-switched networkC TDMD FDM1.30 The network that forwards packets according to host destination addresses is called ( D) network.A circuit-switchedB packet-switchedC virtual-circuitD datagram1.31 The network that forwards packets according to virtual-circuit numbers is called ( C ) network.A circuit-switchedB packet-switchedC virtual-circuitD datagram1.32 The time required to propagate from the beginning of the link to the next router is ( C).A queuing delayB processing delayC propagation delayD transmission delay1.33 Processing delay does not include the time to (B ).A examine the packet’s headerB wait to transmit the packet onto the linkC determine where to direct the packetD check bit-error in the packet1.34 In the following four descriptions, which one is correct? ( C)A The traffic intensity must be greater than 1.B The fraction of lost packets increases as the traffic intensity decreases.C If the traffic intensity is close to zero, the average queuing delay will be closeto zero.D If the traffic intensity is close to one, the average queuing delay will be closeto one.1.35 Suppose, a is the average rate at which packets arrive at the queue, R is the transmission rate, and all packets consist of L bits, then the traffic intensity is ( B ),A LR／aB La／RC Ra／LD LR／a1.36 Suppose there is exactly one packet switch between a sending host and a receiving host. The transmission rates between the sending host and the switch and between the switch and the receiving host are R1 and R2, respectively. Assuming that the switch uses store-and-forward packet switching, what is the total end-to-end delay to send a packet of length L? (Ignore queuing delay, propagation delay, and processing delay.) ( A )A L/R1＋L/R2B L/R1C L/R2D none of the above1.37 We are sending a 30 Mbit MP3 file from a source host to a destination host. Suppose there is only one link between source and destination and the link has a transmission rate of 10 Mbps. Assume that the propagation speed is 2 * 108 meters/sec, and the distance between source and destination is 10,000 km. Also suppose that message switching is used, with the message consisting of the entire MP3 file. How many bits will the source have transmitted when the first bit arrives at the destination?CA. 1 bitB. 30,000,000 bitsC. 500,000 bitsD. none of the above1.38 In the following entries, which is not a kind of access network?(D )A residential accessB company accessC wireless accessD local access1.39 The following technologies may be used for residential access, exceptDA. HFCB. DSLC. Dial-up modemD. FDDI1.40 Which kind of media is not a guided media? ( D)A twisted-pair copper wireB a coaxial cableC fiber opticsD digital satellite channel。

四川大学09-10年计算机网络试题

四川大学09-10年计算机网络试题

四川大学期末考试试题（闭卷）（20010-20011学年第1学期）课程号：课序号：课程名称：计算机网络（A卷）任课教师：吕光宏徐林傅静涛陈黎朱敏杨朝斌适用专业年级：计算机科学技术2008级学生人数：印题份数：学号：姓名：答案写在试卷上，请选择任课教师！！1、Abbreviation Expansion. ( 10points, 1 points for each abbreviation )There are 10 abbreviations of term below. Please expand these abbreviations to the complete terms in either English or Chinese.For Example: RIP : Routing I nformation Protocol /选路信息协议(1). MIME Multiple I nternet Mail Extension 多媒体因特网邮件扩展(2). DNS Domain Name System(3). DHCP Dynami c host configurati on protocol(4). SMTP Simple Mail Transfer Protocol(5). TCP/I P Transmission Control Protocol/Internet Protocol(6). RFC R equest For Comments(7). OSPF Open Shortest Path First(8). NAT N etwork Address Translation(9). PDU protocol data unit(10). CSMA/CD Carrier Sense Multiple Access/Collision Detection2、Multiple Choice(Please answer the following questions. For each question, mark the correct answer. There is exactly one correct answer per question. Y ou are awarded 2 point for each correctly answered question; each wrongly answered question results in 23、terms explanation(10points, 2points for each term)(1) MSS: 最大段长度（1），传输层数据部分的最大长度（1）(2) AIMD线性增加，成倍减少。

川大软院计网选择题答案Chapter3(含答案)

川大软院计网选择题答案Chapter3(含答案)

CHAPTER 3: TRANSPORT LAYER1. A transport-layer protocol provides for logical communication between ___C_.A.RoutersB.HostsC.Application processesD.End systems2.Transport-layer protocols run in __D__.A.ServersB.ClientsC.RoutersD.End systems3.In transport layer, the send side breaks application messages into ___B_, passes to network layer.A.FramesB.SegmentsC.Data-gramsD.bit streams4.The receive side of transport layer reassembles segments into messages, passes to __A__layer.A.ApplicationworkingC.PhysicalD.MAC5.Services provided by transport layer include __C__.A.HTTP and FTPB.TCP and IPC.TCP and UDPD.SMTP6.Which of the following services is not provided by TCPDA.In-order data transfersB.Reliable data transfers and flow controlsC.Congestion controlsD.Delay guarantees and bandwidth guarantees7.These two minimal transport-layer services----___A_ and ____----are the only two services that UDP providesA.process-to-process data delivery, error checkingB.congestion control, reliable data transferC.flow control, congestion controlD.In-order data transfer, error checking8.UDP offers which of the following benefits relative to TCPCA.UDP guarantees that Individual packets of atransmission will arrive “in order”B.UDP supports a self-regulating “throttle”feature that prevents network saturationC.UDP consumes fewer computer resources by notmaintaining connection stateD.None of the above9.Which of the following applications normally uses UDP servicesBA.SMTPB.Streaming multimediaC.FTPD.HTTP10.The job of gathering data chunks, encapsulating each data chunk with header information to create segments and passing the segments to the network is called __A__.A.multiplexingB.de-multiplexingC.forwardingD.routing11.This job of delivering the data in a transport-layer segment to the correct socket is called _B___.A.multiplexingB.de-multiplexingC.forwardingD.routing12.Port number’s scope is ___B_ to ____.A.0, 1023B.0, 65535C.0, 127D.0,25513.The port numbers ranging from __C__to ____ are called well-known port number and are restricted.A.0, 127B.0, 65535C.0, 1023D.0,25514.The UDP header has only four fields, they are__A__.A.Source port number, destination port number, lengthand checksumB.Source port number, destination port number, sourceIP and destination IPC.source IP, destination IP, source MAC address anddestination MAC addressD.source IP, destination IP, sequence number and ACKsequence number15.The field of Length in UDP segment specifies the length of ___B_.A.the UDP segment, not including the headerB.the UDP segment, including the headerC.the UDP segment’s headerD.the Length field16.Which of the following about TCP connection is not correctAA.It is a broadcast connectionB.It is a point-to-point connectionC.It is a pipelined connectionD.It is a full duplex connection17.In the following four descriptions about MSS and MTU, which one is not correctCA.The MSS is typically set by MTUB.The MSS is the maximum size of the TCP segmentincluding headersC.The MSS is the maximum amount of application-layerdata in the segmentD.The MTU means the largest link-layer frame18.__A__ is the byte stream number of first byte in the segment.A.Sequence numberB.ACK numberC.ChecksumD.port number19.__B__ is the byte sequence numbers of next byte expected from other side.A.Sequence numberB.ACK numberC.ChecksumD.port number20.In the following four options, which one is correctDA.Suppose that the last SampleRTT in a TCP connectionis equal to 1 sec. Then the current value of TimeoutInterval will necessarily be≤1 secB.The timeout should be less than the connection’sRTTC.Suppose that the last SampleRTT in a TCP connectionis equal to 1 sec. Then the current value of TimeoutInterval will necessarily be≥1 secD.The variations in the SampleRTT are smoothed out inthe computation of the EstimatedRTT21.There are two 16-bit integers: 1110 0110 0110 0110, 1101 0101 0101 0101. Their checksum is__A__.A.011B.100C.111D.00022.Suppose host A sends host B one TCP segment with sequence number 418, acknowledgement number 571, and 4 bytes of data. Then the sequence number in the acknowledgement to this segment is _____C____A.422B. 418C.571 D. 57523.Because TCP only acknowledges bytes up to the first missing byte in the stream, TCP is said to provide__D__.A.positive ACKsB.Selective acknowledgementsC. 3 duplicate ACKsD.Cumulative acknowledgements24.If we define N to be the window size, base to be the sequence number of the oldest unacknowledged packet, and next-seq-num to be the smallest unused sequence number, then the interval [nextseqnum,base+N-1] corresponds to packet that __A__.A.can be sent immediatelyB.have already been transmitted and acknowledgedC.cannot be usedD.have been sent but not yet acknowledged25.Which of the following is not a pipeliningA.B.Go-Back-NC.Selective repeatD.TCP26.What is the main difference between stop-and-wait and pipelined reliable data transfer protocolBA.The pipelined protocol uses the NAK packets, whereasin the stop-and-wait protocol senders always wait for ACK packets.B.With the pipelined protocol, the sender can sendseveral packets in row, whereas in the stop-and-wait protocol the sender cannot send the packets in row.C.With the pipelined protocol, the receiver must sendone ACK for several packets (cumulative ACK), whereas in the stop-and-wait protocol the receiver can not send the cumulative ACK.D.The pipelined protocol uses timeouts, whereas thestop-and-wait protocol does not use the timeout.27.Fast retransmit means in the case that __D__ duplicate ACK-s are received, the TCP sender resend segment before timer expires.A.6B.5C.4D.328.__B__ is a speeding-matching service---matching the rate which the sender is sending against the rate at which the receiving application is reading.A.congestion controlB.flow controlC.sliding-window controlD.variable control29.TCP provides flow control by having the sender maintaina variable called the __D__.A.bufferB.Congestion windowC.Sliding windowD.Receive window30.Provided RcvBuffer = 20, LastByteRcvd = 20, LastByteRead = 15, then RcvWindow=__B__.A.14B.15C.16D.1031.In the following four descriptions about TCP connection management, which one is not correctDA.Either of the two processes participating in a TCPconnection can end the connectionB.If the FIN bit is set to 1, it means that it wantsto close the connectionC.In the first two step of the three-way handshake,the client and server randomly choose an initial sequence numberD.In the three segments of the three-way handshake, theSYN bit must be set to 132.How does TCP sender perceive congestionDA.Through a timeout eventB.Through a receiving duplicate ACK-s eventC.Both A and BD.Either A or B33.There are two states in TCP congestion control, which are _C___.A.safe start and congestion abandonB.safe start and congestion avoidanceC.slow start and congestion avoidanceD.slow start and congestion abandon34.In TCP, the timeout interval is a function of:AA.estimated RTT at the senderB.MSS and the overhead of a segmentB.the size of buffer at thereceiver D. the size of sending window35.In a TCP connection, there is timeout event when the value of threshold is 32 and the size of congestion window is 16. According to the TCP congestion control policy, the new value of threshold and the new size of congestion window should be ______C__, respectively.A.16,8 B. 24,8 C. 8,1 D. 16, 1。

四川大学高等继续学历教育网络及应用考试题

四川大学高等继续学历教育网络及应用考试题

四川大学高等继续学历教育网络及应用考试题姓名:_________________ 成绩:__________________一、填空题(每空1分，共20分)1、WAN是_________________的所写，LAN是___________________所写。

2、局域网的拓扑结构有___________、_____________、_________________。

3、_____________信号是一种连续变化的电磁波，_____________信号是一种取值为有限个数的电脉冲。

4、常用的差错检测和校正方法有______________和________________。

5、常用的局域网互联设备有__________、__________、_____________、___________等。

6、TCP/IP体系结构的传输层上定义的两个传输协议为___________、__________。

7、常见的IP地址是_________类、_________类和_____________类地址。

8、用户帐号可分为____________、_____________和内置用户帐号几类。

二、选择题(每题1分，共20分)1、一个IP地址占据的比特数是（）A、16B、24C、32D、482、计算机网络协议由（）部分组成。

A、2B、3C、4D、53、两台计算机利用电话线路传输数据时，必备的设备是( )A、同轴电缆B、中继器C、光纤D、调制解调器4、以下IP地址中，属于B类地址的是（）。

A、112.213.12.23B、210.123.23.12C、23.123.213.23D、156.123.32.125、在TCP/IP协议集的层次中，端到端之间通信协议定义在（）。

A、网络接口层B、网间网层C、传输层D、应用层6、在客户机上使用共享文件夹的方法不包括（）。

A、打开“网上邻居”，找到提供文件夹服务的计算机B、在开始菜单的“运行”中输入“\\计算机名\共享名”C、映射用户驱动器D、利用搜索计算机7、当客户端要了解网络某主机的名称或IP地址，可以采用正向查询和（）。

四川大学《计算机通信与网络》期末试题及答案-5135

四川大学《计算机通信与网络》期末试题及答案-5135

四川大学期末考试试题（闭卷）A（ 2008——2009 学年第学年第 1 学期）学期）课程号: 205040030 课序号：课序号： 课程名称：计算机通信与网络 任课教师：任课教师： 严斌宇严斌宇 成绩：成绩： 适用专业年级：2006 学生人数：学生人数： 印题份数：印题份数： 学号：学号： 姓名：姓名：考 试 须 知四川大学学生参加由学校组织或由学校承办的各级各类考试，必须严格执行《四川大学考试工作管理办法》和《四川大学考场规则》。

有考试违纪作弊行为的，一律按照《四川大学学生考试违纪作弊处罚条例》进行处理。

四川大学各级各类考试的监考人员，必须严格执行《四川大学考试工作管理办法》、《四川大学考场规则》和《四川大学监考人员职责》。

有违反学校有关规定的，严格按照《四川大学教学事故认定及处理办法》进行处理。

一、一、选择题（每空2分，共20分，单选题）分，单选题）1. 1. 数据包从源站经过若干个路由器被传递到目的站，在这个过程中，数据包的目的数据包从源站经过若干个路由器被传递到目的站，在这个过程中，数据包的目的ip 地址发生了什么变化 C C 。

A.A.每经过一跳，目的每经过一跳，目的IP 地址就变为下一个路由器的入口地址。

B.B.每经过一跳，目的每经过一跳，目的IP 地址就变为下一个路由器的入口地址。

C.C.目的目的IP 地址在传送过程中不发生变化。

地址在传送过程中不发生变化。

D.D.目的目的IP 地址被第一个路由器改变后就不再发生变化。

2. 2. 术语术语10Base5当中的5表示什么意思？表示什么意思？ C C 。

A. A.使用阻抗为使用阻抗为50欧姆的细缆。

欧姆的细缆。

B. B.使用最大传输距离为使用最大传输距离为50米的双绞线。

米的双绞线。

C. C.使用最大传输距离为使用最大传输距离为500米的粗缆。

米的粗缆。

D.D.使用五类双绞线。

使用五类双绞线。

使用五类双绞线。

3. 3. 在以下设备中，属于数据链路层的有在以下设备中，属于数据链路层的有在以下设备中，属于数据链路层的有 C C 。

四川大学05-06计算机网络考试试题

四川大学05-06计算机网络考试试题

适用专业年级：计算机科学技术2003级 学生人数：学号：学号： 姓名：姓名：考试须知四川大学学生参加由学四川大学学生参加由学校组织或由学校校组织或由学校校组织或由学校承办的各级各类承办的各级各类承办的各级各类考试，考试，必须严格执必须严格执行行《四川大学考试《四川大学考试工作管理办法》工作管理办法》和《四川大学考场规四川大学考场规则》则》。

有考试违纪作弊行为的有考试违纪作弊行为的，一律按照《四，一律按照《四，一律按照《四川大学学生考试川大学学生考试川大学学生考试违纪作弊处罚条违纪作弊处罚条违纪作弊处罚条例》进行处理。

例》进行处理。

例》进行处理。

四川大学各级各类考试四川大学各级各类考试的监考人员的监考人员的监考人员，必须严格，必须严格，必须严格执行《四执行《四执行《四川大学考试工作川大学考试工作川大学考试工作管理办法管理办法管理办法》》.《四川大学《四川大学考场规则考场规则考场规则》和《》和《》和《四川大学监考人四川大学监考人四川大学监考人员职员职责》。

有违反学。

有违反学校有关规定的，校有关规定的，校有关规定的，严格按照《四川严格按照《四川严格按照《四川大学教学事故认大学教学事故认大学教学事故认定及处理办法》定及处理办法》定及处理办法》进行处理。

进行处理。

题 号 一 二 三 四 五 六 七 八 九 十 得 分 阅卷教师 阅卷时间总 成 绩期末卷面 %期中卷面 %实验成绩 %考勤成绩 %8. 网络地址表示中，网络地址表示中，下面哪种说法正下面哪种说法正下面哪种说法正确（确（确（ ）。

A.网络地址全为1 B . 主机地址全为1 C. 网络地网络地址全为址全为0 D. 主机地址主机地址全为全为0 9. 把IP 地址转换为MAC 地址的协议称为（地址的协议称为（ ）。

A . IGP B . RIP Ｃ. ARP D. RARP 10. 对于下列对于下列说法，哪一种是说法，哪一种是说法，哪一种是错误的（错误的（错误的（ ）。

(完整版)川大软院计网选择题答案Chapter3(含答案)

(完整版)川大软院计网选择题答案Chapter3(含答案)

CHAPTER 3: TRANSPORT LAYER1. A transport-layer protocol provides for logical communication between ___C_.A.RoutersB.HostsC.Application processesD.End systems2.Transport-layer protocols run in __D__.A.ServersB.ClientsC.RoutersD.End systems3.In transport layer, the send side breaks application messages into ___B_, passes tonetwork layer.A.FramesB.SegmentsC.Data-gramsD.bit streams4.The receive side of transport layer reassembles segments into messages, passes to__A__layer.A.ApplicationworkingC.PhysicalD.MAC5.Services provided by transport layer include __C__.A.HTTP and FTPB.TCP and IPC.TCP and UDPD.SMTP6.Which of the following services is not provided by TCP?DA.In-order data transfersB.Reliable data transfers and flow controlsC.Congestion controlsD.Delay guarantees and bandwidth guarantees7.These two minimal transport-layer services----___A_ and ____----are the only twoservices that UDP providesA.process-to-process data delivery, error checkingB.congestion control, reliable data transferC.flow control, congestion controlD.In-order data transfer, error checking8.UDP offers which of the following benefits relative to TCP?CA.UDP guarantees that Individual packets of a transmission will arrive “infeature that prevents networkB.UDP supports a self-regulating “throttle”　saturationC.UDP consumes fewer computer resources by not maintaining connection stateD.None of the above9.Which of the following applications normally uses UDP services?BA.SMTPB.Streaming multimediaC.FTPD.HTTP10.The job of gathering data chunks, encapsulating each data chunk with headerinformation to create segments and passing the segments to the network is called__A__.A.multiplexingB.de-multiplexingC.forwardingD.routing11.This job of delivering the data in a transport-layer segment to the correct socket iscalled _B___.A.multiplexingB.de-multiplexingC.forwardingD.routingB_ to ____.12.Port number’s scope is ___A.0, 1023B.0, 65535C.0, 127D.0,25513.The port numbers ranging from __C__to ____ are called well-known port numberand are restricted.A.0, 127B.0, 65535C.0, 1023D.0,25514.The UDP header has only four fields, they are__A__.A.Source port number, destination port number, length and checksumB.Source port number, destination port number, source IP and destination IPC.source IP, destination IP, source MAC address and destination MAC addressD.source IP, destination IP, sequence number and ACK sequence number15.The field of Length in UDP segment specifies the length of ___B_.A.the UDP segment, not including the headerB.the UDP segment, including the headerC.the UDP segment’s headerD.the Length field16.Which of the following about TCP connection is not correct?AA.It is a broadcast connectionB.It is a point-to-point connectionC.It is a pipelined connectionD.It is a full duplex connection17.In the following four descriptions about MSS and MTU, which one is not correct?CA.The MSS is typically set by MTUB.The MSS is the maximum size of the TCP segment including headersC.The MSS is the maximum amount of application-layer data in the segmentD.The MTU means the largest link-layer frame18.__A__ is the byte stream number of first byte in the segment.A.Sequence numberB.ACK numberC.ChecksumD.port number19.__B__ is the byte sequence numbers of next byte expected from other side.A.Sequence numberB.ACK numberC.ChecksumD.port number20.In the following four options, which one is correct?DA.Suppose that the last SampleRTT in a TCP connection is equal to 1 sec. Thenthe current value of TimeoutInterval will necessarily be≤1 secB.The timeout should be less than the connection’s RTTC.Suppose that the last SampleRTT in a TCP connection is equal to 1 sec. Thenthe current value of TimeoutInterval will necessarily be≥1 secD.The variations in the SampleRTT are smoothed out in the computation of theEstimatedRTT21.There are two 16-bit integers: 1110 0110 0110 0110, 1101 0101 0101 0101. Theirchecksum is__A__.A.0100010001000011B.1011101110111100C.1111111111111111D.100000000000000022.Suppose host A sends host B one TCP segment with sequence number 418,acknowledgement number 571, and 4 bytes of data. Then the sequence number in the acknowledgement to this segment is _____C____A.422B. 418C. 571D. 57523.Because TCP only acknowledges bytes up to the first missing byte in the stream,TCP is said to provide__D__.A.positive ACKsB.Selective acknowledgementsC. 3 duplicate ACKsD.Cumulative acknowledgements24.If we define N to be the window size, base to be the sequence number of the oldestunacknowledged packet, and next-seq-num to be the smallest unused sequence number, then the interval [nextseqnum,base+N-1] corresponds to packet that __A__.A.can be sent immediatelyB.have already been transmitted and acknowledgedC.cannot be usedD.have been sent but not yet acknowledged25.Which of the following is not a pipelining protocol.AA.Rdt1.0B.Go-Back-NC.Selective repeatD.TCP26.What is the main difference between stop-and-wait and pipelined reliable datatransfer protocol?BA.The pipelined protocol uses the NAK packets, whereas in the stop-and-waitprotocol senders always wait for ACK packets.B.With the pipelined protocol, the sender can send several packets in row,whereas in the stop-and-wait protocol the sender cannot send the packets inrow.C.With the pipelined protocol, the receiver must send one ACK for severalpackets (cumulative ACK), whereas in the stop-and-wait protocol the receivercan not send the cumulative ACK.D.The pipelined protocol uses timeouts, whereas the stop-and-wait protocol doesnot use the timeout.27.Fast retransmit means in the case that __D__ duplicate ACK-s are received, theTCP sender resend segment before timer expires.A.6B.5C.4D.328.__B__ is a speeding-matching service---matching the rate which the sender issending against the rate at which the receiving application is reading.A.congestion controlB.flow controlC.sliding-window controlD.variable control29.TCP provides flow control by having the sender maintain a variable called the__D__.A.bufferB.Congestion windowC.Sliding windowD.Receive window30.Provided RcvBuffer = 20, LastByteRcvd = 20, LastByteRead = 15, thenRcvWindow=__B__.A.14B.15C.16D.1031.In the following four descriptions about TCP connection management, which oneis not correct?DA.Either of the two processes p articipating in a TCP connection can end theconnectionB.If the FIN bit is set to 1, it means that it wants to close the connectionC.In the first two step of the three-way handshake, the client and server randomlychoose an initial sequence numberD.In the three segments of the three-way handshake, the SYN bit must be set to132.How does TCP sender perceive congestion?DA.Through a timeout eventB.Through a receiving duplicate ACK-s eventC.Both A and BD.Either A or B33.There are two states in TCP congestion control, which are _C___.A.safe start and congestion abandonB.safe start and congestion avoidanceC.slow start and congestion avoidanceD.slow start and congestion abandon34.In TCP, the timeout interval is a function of:AA.estimated RTT at the senderB. MSS and the overhead of a segmentB.the size of buffer at the receiver D. the size of sending window35.In a TCP connection, there is timeout event when the value of threshold is 32 andthe size of congestion window is 16. According to the TCP congestion control policy, the new value of threshold and the new size of congestion window should be ______C__, respectively.A.16, 8B. 24, 8C. 8, 1D. 16, 1。

四川大学计算机网络与通信期末考试08-09A

四川大学计算机网络与通信期末考试08-09A

四川大学期末考试试题（A）闭卷
（2008 ——2009 学年第 2 学期）
课程号：30306230课序号：0 7 课程名称：计算机网络与通信任课教师：成绩：适用专业年级：05 学生人数：印题份数：学号：姓名：
注：1试题字迹务必清晰，书写工整。

本题 4 页，本页为第 1 页
2 题间不留空，一般应题卷分开教务处试题编号：
3务必用A4纸打印
注：1试题字迹务必清晰，书写工整。

本题 4 页，本页为第 2 页
2 题间不留空，一般应题卷分开教务处试题编号：
3务必用A4纸打印
2 题间不留空，一般应题卷分开教务处试题编号：3务必用A4纸打印
注：1试题字迹务必清晰，书写工整。

本题 4 页，本页为第 4 页
2 题间不留空，一般应题卷分开教务处试题编号：
3务必用A4纸打印。

川大软院计网选择题答案Chapter5(含答案)

川大软院计网选择题答案Chapter5(含答案)

1. A ( D) protocol is used to move a packet over an individual 独立link.A. application-layerB. transport-layerC. network-layerD. link-layer2. Which of the following services can not offered by a link-layer protocol? ( )A. congestion controlB. Link AccessC. Error controlD. FramingHint：framing, link access，reliable delivery，flow control，error detection，error correction，half-duplex and full-duplex3. ( B ) protocol serves to 为……服务coordinate 协调the frame transmissionsof the many nodes when multiple nodes share a single broadcast link.A. ARPB. MACC. ICMPD. DNS4. Consider CRC error checking approach, the four bit generator G is 1011, andsuppose that the data D is 10101010, then the value of R is ( A).A. 010B. 100C. 011D. 1105. In the following four descriptions说明about random access protocol, whichone is not correct? ( A )A. In slotted ALOHA, nodes can transmit at random time.B. CSMA/CD cannot be implemented on a wireless channel.C. The maximum efficiency of a slotted ALOHA is higher than a pure ALOHA.D. In CSMA/CD, one node listens to the channel before transmitting.6. In the following descriptions about MAC address, which one is not correct?( D )A. The MAC address is the address of one node’s adapter.B. No two adapters have the same MAC address.C. The MAC address doesn’t change no matter where the adapter goes.D. MAC address has a hierarchical structure分层结构.MAC：flat structureIP：hierarchical structure7. The ARP protocol can translate ( ) into ( ). ( C )A. host name, IP addressB. host name, MAC addressC. IP address, MAC addressD. broadcast address, IP address8. The value of Preamble field in Ethernet frame structure is ( C)A. 10101010 10101010……10101010 11111111B. 10101011 10101011……10101011 10101011C. 10101010 10101010……10101010 10101011D. 10101010 10101010……10101010 101010109. In CSMA/CD, the adapter waits some time and then returns to sensing thechannel. In the following four times, which one is impossible? ( D)A. 0 bit timesB. 512 bit timesC. 1024 bit timesD. 1028 bit times10. The principal components of PPP include but not( D ).A. framingB. physical-control protocolC. link-layer protocolD. network-layer protocol11. Consider the data D is 01110010001, if use even parity checking approach, theparity bit is( ① ), if use odd parity checking approach, the parity bit is( ② ). ( D )A. ① 0 ② 1B. ① 0 ② 0C. ① 1 ② 1D. ① 1 ② 012. In the following four descriptions, which one is not correct? (B )A. Switches can interconnect different LAN technologies.B. Hubs can interconnect different LAN technologies.C. There is no limit to how large a LAN can be when switches are used tointerconnect LAN segments.D. There is restriction on the maximum allowable number of nodes in a collisiondomain when hubs are used to interconnect LAN segments.13. Which of the following devices is not a plug and play device? ( B )A. hubB. routerC. switchD. repeater14. Which device has the same collision domain? ( A )A. HubB. SwitchC. RouteD. Bridge15. In data link-layer, which protocol is used to share bandwidth? ( D)A. SMTPB. ICMPC. ARPD. CSMA/CD16. When two or more nodes on the LAN segments transmit at the same time, therewill be a collision and all of the transmitting nodes well enter exponential back-off, that is all of the LAN segments belong to the same( A ).A. collision domainB. switchC. bridgeD. hub17. In the following four descriptions about PPP, which one is not correct? ( D )A. PPP is required to detect and correct errors.B. PPP is not required to deliver frames to the link receiver in the same order inwhich they were sent by the link sender.C. PPP need only operate over links that have a single sender and a singlereceiver.D. PPP is not required to provide flow control.18. For ( A ) links that have a single sender at one end of the link and a singlereceiver at the other end of the link.A. point-to-pointB. broadcastC. multicastD. all of the above19. With(B )transmission, the nodes at both ends of a link may transmit packets atthe same time.A. half-duplexB. full-duplexC. simplex(单工)D.synchronous20. Which of the following is wrong? ( A )A. ARP table is configured by a system administratorB. ARP table is built automaticallyC. ARP table is dynamicD. ARP table maps IP addresses to MAC addresses21. In LAN, if UTP is used, the common connector is (C ).A. AUIB. BNCC. RJ-45D. NNI22. Which of the following four descriptions about MAC addresses is wrong? ( C )A. a MAC address is burned into the adapter’s ROMB. No two adapters have the same addressC. An adapter’s MAC address is dynamicD. A MAC address is a link-layer address23. In the CSMA/CD protocol, what condition on the transmission delay andthe propagation delay has to be satisfied to guarantee that a node always detects a collision? BA. B.C. D.。

(完整版)川大软院计网选择题答案Chapter3(含答案)

(完整版)川大软院计网选择题答案Chapter3(含答案)

CHAPTER 3: TRANSPORT LAYER1. A transport-layer protocol provides for logical communication between ___C_.A.RoutersB.HostsC.Application processesD.End systems2.Transport-layer protocols run in __D__.A.ServersB.ClientsC.RoutersD.End systems3.In transport layer, the send side breaks application messages into ___B_, passes tonetwork layer.A.FramesB.SegmentsC.Data-gramsD.bit streams4.The receive side of transport layer reassembles segments into messages, passes to__A__layer.A.ApplicationworkingC.PhysicalD.MAC5.Services provided by transport layer include __C__.A.HTTP and FTPB.TCP and IPC.TCP and UDPD.SMTP6.Which of the following services is not provided by TCP?DA.In-order data transfersB.Reliable data transfers and flow controlsC.Congestion controlsD.Delay guarantees and bandwidth guarantees7.These two minimal transport-layer services----___A_ and ____----are the only twoservices that UDP providesA.process-to-process data delivery, error checkingB.congestion control, reliable data transferC.flow control, congestion controlD.In-order data transfer, error checking8.UDP offers which of the following benefits relative to TCP?CA.UDP guarantees that Individual packets of a transmission will arrive “in order”B.UDP supports a self-regulating “throttle” feature that prevents networksaturationC.UDP consumes fewer computer resources by not maintaining connection stateD.None of the above9.Which of the following applications normally uses UDP services?BA.SMTPB.Streaming multimediaC.FTPD.HTTP10.The job of gathering data chunks, encapsulating each data chunk with headerinformation to create segments and passing the segments to the network is called __A__.A.multiplexingB.de-multiplexingC.forwardingD.routing11.This job of delivering the data in a transport-layer segment to the correct socket iscalled _B___.A.multiplexingB.de-multiplexingC.forwardingD.routing12.Port number’s scope is ___B_ to ____.A.0, 1023B.0, 65535C.0, 127D.0,25513.The port numbers ranging from __C__to ____ are called well-known port numberand are restricted.A.0, 127B.0, 65535C.0, 1023D.0,25514.The UDP header has only four fields, they are__A__.A.Source port number, destination port number, length and checksumB.Source port number, destination port number, source IP and destination IPC.source IP, destination IP, source MAC address and destination MAC addressD.source IP, destination IP, sequence number and ACK sequence number15.The field of Length in UDP segment specifies the length of ___B_.A.the UDP segment, not including the headerB.the UDP segment, including the headerC.the UDP segment’s headerD.the Length field16.Which of the following about TCP connection is not correct?AA.It is a broadcast connectionB.It is a point-to-point connectionC.It is a pipelined connectionD.It is a full duplex connection17.In the following four descriptions about MSS and MTU, which one is not correct?CA.The MSS is typically set by MTUB.The MSS is the maximum size of the TCP segment including headersC.The MSS is the maximum amount of application-layer data in the segmentD.The MTU means the largest link-layer frame18.__A__ is the byte stream number of first byte in the segment.A.Sequence numberB.ACK numberC.ChecksumD.port number19.__B__ is the byte sequence numbers of next byte expected from other side.A.Sequence numberB.ACK numberC.ChecksumD.port number20.In the following four options, which one is correct?DA.Suppose that the last SampleRTT in a TCP connection is equal to 1 sec. Thenthe current value of TimeoutInterval will necessarily be≤1 secB.The timeout should be less than the connection’s RTTC.Suppose that the last SampleRTT in a TCP connection is equal to 1 sec. Thenthe current value of TimeoutInterval will necessarily be≥1 secD.The variations in the SampleRTT are smoothed out in the computation of theEstimatedRTT21.There are two 16-bit integers: 1110 0110 0110 0110, 1101 0101 0101 0101. Theirchecksum is__A__.A.0100010001000011B.1011101110111100C.1111111111111111D.100000000000000022.Suppose host A sends host B one TCP segment with sequence number 418,acknowledgement number 571, and 4 bytes of data. Then the sequence number in the acknowledgement to this segment is _____C____A.422B. 418C. 571D. 57523.Because TCP only acknowledges bytes up to the first missing byte in the stream,TCP is said to provide__D__.A.positive ACKsB.Selective acknowledgementsC. 3 duplicate ACKsD.Cumulative acknowledgements24.If we define N to be the window size, base to be the sequence number of the oldestunacknowledged packet, and next-seq-num to be the smallest unused sequence number, then the interval [nextseqnum,base+N-1] corresponds to packet that __A__.A.can be sent immediatelyB.have already been transmitted and acknowledgedC.cannot be usedD.have been sent but not yet acknowledged25.Which of the following is not a pipelining protocol.AA.Rdt1.0B.Go-Back-NC.Selective repeatD.TCP26.What is the main difference between stop-and-wait and pipelined reliable datatransfer protocol?BA.The pipelined protocol uses the NAK packets, whereas in the stop-and-waitprotocol senders always wait for ACK packets.B.With the pipelined protocol, the sender can send several packets in row,whereas in the stop-and-wait protocol the sender cannot send the packets inrow.C.With the pipelined protocol, the receiver must send one ACK for severalpackets (cumulative ACK), whereas in the stop-and-wait protocol the receivercan not send the cumulative ACK.D.The pipelined protocol uses timeouts, whereas the stop-and-wait protocol doesnot use the timeout.27.Fast retransmit means in the case that __D__ duplicate ACK-s are received, theTCP sender resend segment before timer expires.A.6B.5C.4D.328.__B__ is a speeding-matching service---matching the rate which the sender issending against the rate at which the receiving application is reading.A.congestion controlB.flow controlC.sliding-window controlD.variable control29.TCP provides flow control by having the sender maintain a variable called the__D__.A.bufferB.Congestion windowC.Sliding windowD.Receive window30.Provided RcvBuffer = 20, LastByteRcvd = 20, LastByteRead = 15, thenRcvWindow=__B__.A.14B.15C.16D.1031.In the following four descriptions about TCP connection management, which oneis not correct?DA.Either of the two processes participating in a TCP connection can end theconnectionB.If the FIN bit is set to 1, it means that it wants to close the connectionC.In the first two step of the three-way handshake, the client and server randomlychoose an initial sequence numberD.In the three segments of the three-way handshake, the SYN bit must be set to132.How does TCP sender perceive congestion?DA.Through a timeout eventB.Through a receiving duplicate ACK-s eventC.Both A and BD.Either A or B33.There are two states in TCP congestion control, which are _C___.A.safe start and congestion abandonB.safe start and congestion avoidanceC.slow start and congestion avoidanceD.slow start and congestion abandon34.In TCP, the timeout interval is a function of:AA.estimated RTT at the senderB. MSS and the overhead of a segmentB.the size of buffer at the receiver D. the size of sending window35.In a TCP connection, there is timeout event when the value of threshold is 32 andthe size of congestion window is 16. According to the TCP congestion control policy, the new value of threshold and the new size of congestion window should be ______C__, respectively.A.16, 8B. 24, 8C. 8, 1D. 16, 1。

川大软院计网选择题答案Chapter5(含答案)

川大软院计网选择题答案Chapter5(含答案)

1. A ( D) protocol is used to move a packet over an individual 独立link.A. application-layerB. transport-layerC. network-layerD. link-layer2. Which of the following services can not offered by a link-layer protocol? ( )A. congestion controlB. Link AccessC. Error controlD. FramingHint：framing, link access，reliable delivery，flow control，error detection，error correction，half-duplex and full-duplex3. ( B ) protocol serves to 为……服务coordinate 协调the frame transmissionsof the many nodes when multiple nodes share a single broadcast link.A. ARPB. MACC. ICMPD. DNS4. Consider CRC error checking approach, the four bit generator G is 1011, andsuppose that the data D is 10101010, then the value of R is ( A).A. 010B. 100C. 011D. 1105. In the following four descriptions说明about random access protocol, whichone is not correct? ( A )A. In slotted ALOHA, nodes can transmit at random time.B. CSMA/CD cannot be implemented on a wireless channel.C. The maximum efficiency of a slotted ALOHA is higher than a pure ALOHA.D. In CSMA/CD, one node listens to the channel before transmitting.6. In the following descriptions about MAC address, which one is not correct? ( D )A. The MAC address is the address of one node’s ada pter.B. No two adapters have the same MAC address.C. The MAC address doesn’t change no matter where the adapter goes.D. MAC address has a hierarchical structure分层结构.MAC：flat structureIP：hierarchical structure7. The ARP protocol can translate ( ) into ( ). ( C )A. host name, IP addressB. host name, MAC addressC. IP address, MAC addressD. broadcast address, IP address8. The value of Preamble field in Ethernet frame structure is ( C)A. 10101010 10101010……10101010 11111111B. 10101011 10101011……10101011 10101011C. 10101010 10101010……10101010 10101011D. 10101010 10101010……10101010 101010109. In CSMA/CD, the adapter waits some time and then returns to sensing thechannel. In the following four times, which one is impossible? ( D)A. 0 bit timesB. 512 bit timesC. 1024 bit timesD. 1028 bit times10. The principal components of PPP include but not( D ).A. framingB. physical-control protocolC. link-layer protocolD. network-layer protocol11. Consider the data D is 01110010001, if use even parity checking approach, theparity bit is( ① ), if use odd parity checking approach, the parity bit is( ② ). ( D )A. ① 0 ② 1B. ① 0 ② 0C. ① 1 ② 1D. ① 1 ② 012. In the following four descriptions, which one is not correct? (B )A. Switches can interconnect different LAN technologies.B. Hubs can interconnect different LAN technologies.C. There is no limit to how large a LAN can be when switches are used tointerconnect LAN segments.D. There is restriction on the maximum allowable number of nodes in a collisiondomain when hubs are used to interconnect LAN segments.13. Which of the following devices is not a plug and play device? ( B )A. hubB. routerC. switchD. repeater14. Which device has the same collision domain? ( A )A. HubB. SwitchC. RouteD. Bridge15. In data link-layer, which protocol is used to share bandwidth? ( D)A. SMTPB. ICMPC. ARPD. CSMA/CD16. When two or more nodes on the LAN segments transmit at the same time, therewill be a collision and all of the transmitting nodes well enter exponential back-off, that is all of the LAN segments belong to the same( A ).A. collision domainB. switchC. bridgeD. hub17. In the following four descriptions about PPP, which one is not correct? ( D )A. PPP is required to detect and correct errors.B. PPP is not required to deliver frames to the link receiver in the same order inwhich they were sent by the link sender.C. PPP need only operate over links that have a single sender and a single receiver.D. PPP is not required to provide flow control.18. For ( A ) links that have a single sender at one end of the link and a single receiverat the other end of the link.A. point-to-pointB. broadcastC. multicastD. all of the above19. With(B )transmission, the nodes at both ends of a link may transmit packets at thesame time.A. half-duplexB. full-duplexC. simplex(单工)D.synchronous20. Which of the following is wrong? ( A )A. ARP table is configured by a system administratorB. ARP table is built automaticallyC. ARP table is dynamicD. ARP table maps IP addresses to MAC addresses21. In LAN, if UTP is used, the common connector is (C ).A. AUIB. BNCC. RJ-45D. NNI22. Which of the following four descriptions about MAC addresses is wrong? ( C )A. a MAC address is burned into the adapter’s ROMB. No two adapters have the same addressC. An adapter’s MAC address is dynamicD. A MAC address is a link-layer address23. In the CSMA/CD protocol, what condition on the transmission delay and thepropagation delay has to be satisfied to guarantee that a node always detects a collision? BA. B.C. D.。

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1. A ( ) protocol is used to move a packet over an individual link.A. application-layerB. transport-layerC. network-layerD. link-layer2. Which of the following services can not offered by a link-layer protocol? ( )A. congestion controlB. Link AccessC. Error controlD. Framing3. ( ) protocol serves to coordinate the frame transmissions of the many nodes when multiple nodes share a single broadcast link.A. ARPB. MACC. ICMPD. DNS4. Consider CRC error checking approach, the four bit generator G is 1011, and suppose that the data D is 10101010, then the value of R is ( ).A. 010B. 100C. 011D.1105. In the following four descriptions about random access protocol, which one is not correct? ( )A. In slotted ALOHA, nodes can transmit at random time.B. CSMA/CD cannot be implemented on a wireless channel.C. The maximum efficiency of a slotted ALOHA is higher than a pure ALOHA.D. In CSMA/CD, one node listens to the channel before transmitting.6. In the following descriptions about MAC address, which one is not correct? ( )A. The MAC address is the address of one node’s adapter.B. No two adapters have the same MAC address.C. The MAC address doesn’t change no matter where the adapter goes.D. MAC address has a hierarchical structure.7. The ARP protocol can translate ( ) into ( ). ( )A. host name, IP addressB. host name, MAC addressC. IP address, MAC addressD. broadcast address, IP address8. The value of Preamble field in Ethernet frame structure is ( )A. 10101010 10101010……10101010 11111111B. 10101011 10101011……10101011 10101011C. 10101010 10101010……10101010 10101011D. 10101010 10101010……10101010 101010109. In CSMA/CD, the adapter waits some time and then returns to sensing the channel. In the following four times, which one is impossible? ( )A. 0 bit timesB. 512 bit timesC. 1024 bit timesD. 1028 bit times10. The principal components of PPP include but not( ).A. framingB. physical-control protocolC. link-layer protocolD. network-layer protocol11. Consider the data D is 01110010001, if use even parity checking approach, the parity bit is( ① ), if use odd parity checking approach, the parity bit is( ② ). ( )A. ① 0 ② 1B. ① 0 ② 0C. ① 1 ② 1D. ① 1 ② 012. In the following four descriptions, which one is not correct? ( )A. Switches can interconnect different LAN technologies.B. Hubs can interconnect different LAN technologies.C. There is no limit to how large a LAN can be when switches are used to interconnectLAN segments.D. There is restriction on the maximum allowable number of nodes in a collision domain when hubs are used to interconnect LAN segments.13. Which of the following devices is not a plug and play device? ( )A. hubB. routerC. switchD. repeater14. Which device has the same collision domain? ( )A. HubB. SwitchC. RouteD. Bridge15. In data link-layer, which protocol is used to share bandwidth? ( )A. SMTPB. ICMPC. ARPD. CSMA/CD16. When two or more nodes on the LAN segments transmit at the same time, there will be a collision and all of the transmitting nodes well enter exponential back-off, that is all of the LAN segments belong to the same( ).A. collision domainB. switchC. bridgeD. hub17. In the following four descriptions about PPP, which one is not correct? ( )A. PPP is required to detect and correct errors.B. PPP is not required to deliver frames to the link receiver in the same order in which they were sent by the link sender.C. PPP need only operate over links that have a single sender and a single receiver.D. PPP is not required to provide flow control.18. For ( ) links that have a single sender at one end of the link and a single receiver at the other end of the link.A. point-to-pointB. broadcastC. multicastD. all of the above19. With( )transmission, the nodes at both ends of a link may transmit packets at the same time.A. half-duplexB. full-duplexC. simplex(单工)D. synchronous20. Which of the following is wrong? ( )A. ARP table is configured by a system administratorB. ARP table is built automaticallyC. ARP table is dynamicD. ARP table maps IP addresses to MAC addresses21. In LAN, if UTP is used, the common connector is ( ).A. AUIB. BNCC. RJ-45D. NNI22. Which of the following four descriptions about MAC addresses is wrong? ( )A. a MAC address is burned into the adapter’s ROMB. No two adapters have the same addressC. An adapter’s MAC address is dynamicD. A MAC address is a link-layer address23. In the CSMA/CD protocol, what condition on the transmission delay and the propagation delay has to be satisfied to guarantee that a node always detects a collision?A.B.C. D.。

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