川大软院计网选择题答案Chapter4含答案.doc

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 datagramnetwork, the forwarding decision is based on the value of the _B field in the packet header.A.source addressB.destination addressC.labelD.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 packet fields are updated? _C_A.Source IP addressB.Destination IP addressC.ChecksumD.Destination port number7.Which of the following IP address doesnt belong to the /25 network? _D_A.B.1C.20D.298.You 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 the network. What subnet mask can you use to create the subnets necessary to meet the given criteria? _C_A.B.28C.24D.409.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 TimeExceed12.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 arecorrect13._B_ allows a site to use a set of private addresses for internal communication 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 ?CA./22B./21C./23D./2416.What is the limited broadcast address corresponding to the node with the following IP address: 9?DA.55B.55C.55D.None of the above17.In classful IP addressing, how many network bits does 6 have?AA.8B.16C.24D.3218.What is the broadcast IP address for 28 / 26 ?DA.28B.27C.3D.9119.Whats a network? From IP address perspective they can physically reach each other 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 Internets network layer has three major components, the first component is the 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 50/29, the network address for this network is_.A（）A.48B.50C.D.22.There are two 16-bit integers: 1110 0110 0110 0110, 1101 0101 0101 0101. Their checksum isA_.A.0100010001000011B.1011101110111100C.1111111111111111D.100000000000000023.The use of hierarchy in routing tables can _A_ the size of the routing tables.A.reduceB.increaseC.neither reduce nor increaseD.None of the choices are correct24.Which of the following protocol doesnt 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_ rou