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1、Chapter 4 The Network Layer1What is the name of a network-layer packet?（ ）A. message B. segment C. datagram D. frame 2What are the two most important network-layer functions in a datagram network? （ ）A. forwarding & routing B. forwarding & filteringC. routing & detecting D. routing & checking3When a

2、 packet arrives at a routers input link, the router must move the packet to the appropriate output link, this action is called _? （ ）A. Forwarding B. routing C. cut through D. filtering4The network layer must determine the path taken by packets as they flow from a sender to a receiver. This action i

3、s called_? （ ）A. Forwarding B. routing C. cut through D. examine5A router forwards a packet by examining the value of a field in the arriving packets header, and then using this value to index into the routers forwarding table, this value is? （ ）A. destination IP address B. source IP addressC. desti

4、nation MAC address D. source MAC address6IP belongs to _ layer? （ ）A. transport B. network C. data link D. physical 7Which layer provides host-to-host services? （ ）A. transport B. network C. data link D. physical8Which layer provides a connection service called virtual-circuit networks and a connect

5、ionless service called datagram networks? （ ）A. transport B. network C. data link D. physical9IPV4 has a _ bit address? （ ）A. 48 B. 16 C. 32 D. 6410MAC address is _ bits? （ ）A. 48 B. 16 C. 32 D. 6411The Internets network layer has three major components, the first component is the IP protocol, the s

6、econd component is the routing protocol, the final component is_? （ ）A. forwarding B. address translation C. check D. ICMP12How many bits specify the IP protocol version in a datagram? （ ）A. 1 bit B. 2 bits C. 4 bits D. 8 bits13Most IPV4 datagram do not contain option field, how many bytes a header

7、has in a typical IP datagram? （ ）A. 4 bytes B. 8 bytes C. 16 bytes D. 20 bytes14How many bits used in IP datagram express total length of the IP datagram? （ ）A. 4 bits B. 8 bits C. 16 bits D. 20 bits15Data-grams are rarely larger than _?（ ）A. 1500 bytes B. 65535 bytes C. 500 bytes D. 1024 bytes16New

8、 version of IP-IPV6 does not allow fragment in _?（ ）A. RouterB. HostC. Both of above D. None of above17How does the TTL changed by one each time the datagram is processed by a router? （ ）A. decrease B. increase C. no change D. always 018Which layer protocol is indicated by the value of protocol fiel

9、d in IP datagram? （ ）A. application B. transport C. network D. data link19IP option is dropped in the _ header. （ ）A. IPv6 B. IPv4 C. TCP D. UDP20The data field in IP datagram can carry many types of data except _. （ ）A. TCP B. UDP C. ICMP D. MAC21ICMP is used for_?（ ）A. Reliable data transferB. Err

10、or reportingC. Flow control D. Congestion control22Suppose you receive an IP datagram from one link and check your forwarding table to determine the outgoing link, but this outgoing link has an MTU that is smaller than the length of IP datagram. Which technology will be used? （ ）A. resend B. discard

11、 C. fragment D. none 23The designer of IPv4 decided to put the job of datagram reassembly in_.（ ）A. router B. switch C. hub D. end system24IP addressing assigns an address to 50/29, the network address for this network is_.（ ）A. 48 B. 50 C. D. 223.10.

12、0.025If all data-grams arriving at the router from WAN have the same destination IP address, then how does the router know the internal host to which it should forward a given datagram? The trick is to use _ table at router, and include port numbers as well as IP address in the table entries. （ ）A.

13、routing B. forwarding C. ARP D. NAT translation26When running a Telnet, FTP, or HTTP session, you may have encountered an error message such as “Destination network un-reachable”, This message had its origin in _. （ ）A. IGMP B. EGP C. ICMP D. BGP27The well-known ping program sends an (a) _ type 8 co

14、de 0 message to the specified host. The destination hosts seeing the echo request, send back a type 0 code 0 ICMP echo reply. （ ）A. ICMP B. IGMP C. TCP D. UDP28Tracer-out is implemented with _ messages. （ ）A. IGMP B. TCP C. UDP D. ICMP29The standard Tracer-out program actually sends sets of _ packet

15、s with the same TTL. （ ）A. one B. two C. three D. four30IPv6 increases the size of the IP address from 32bit to _ bit. （ ）A. 64 B. 128 C. 256 D. 51231How many bytes are there in header of IPv6? （ ）A. 8 B. 20 C. 40 D. 3232IPv6 does not allow for fragmentation and reassembly at inter-media _. （ ）A. ro

16、uters B. switches C. end system D. hubs33From sender to receivers, all packets will take the same path, this is we use a _ service. （ ）A. datagram B. VC C. circuit D. Ethernet34_ means moving packets from routers input port to appropriate router output port? （ ）A. forwarding B. filtering C. routing

17、D. switching35_ means determining route taken by packets from source to destination? （ ）A. forwarding B. filtering C. routing D. switching36A router works in _ layer? （ ）A. NetworkingB. Data linkC. ApplicationD. Physical37A switch works in _ layer? （ ）A. NetworkingB. Data linkC. ApplicationD. Physic

18、al38Networking layer provides services between two _.（ ）A. HostsB. ProcessesC. ApplicationsD. Machines39Link layer provides services between two _. （ ）A. HostsB. ProcessesC. ApplicationsD. Machines40The internets network layer provides a single service-that is _.（ ）A. Reliable data transferB. Flow c

19、ontrolC. Congestion controlD. Best-effort-service41Datagram network provides network-layer_.（ ）A. connectionless serviceB. connection serviceC. both of aboveD. neither of A and B42VC network provides network-layer _. （ ）A. connectionless serviceB. connection serviceC. both of aboveD. neither of A an

20、d B43In VC network, each packet carries _. （ ）A. VC identifierB. destination host addressC. IP address D. Mac address44A VC consists of three part, this three parts do not include_. （ ）A. Path from source to destinationB. VC numbers, one number for each link along pathC. Entries in forwarding tables

21、 in routers along pathD. Destination address45. In _ networking, a series of packet may follow different paths and may arrive out of order? （ ）A. DatagramB. VCC. TCPD. None of above46The internet is a (an) _ network? （ ）A. DatagramB. VCC. Both of aboveD. None of above47The four components of a route

22、r do not include_? （ ）A. Input and output portsB. Switch fabricC. Routing processorD. Switching processor48There are three kinds of switch fabric for a router normally, those three switch fabric do not includes_?（ ）A. Switching via memoryB. Switching via a busC. Switching via an Interconnection-Netw

23、orkD. Packet switching49Which of the following protocol is used for error reporting? （ ）A. ICMPB. TCPC. IPD. UDP50Which of the following is not a routing protocol? （ ）A. TCPB. RIPC. OSPFD. BGP51IPV4 has a _ bits address? （ ）A. 32B. 64C. 16D. 12852IP address is identifier for _. （ ）A. HostB. Router i

24、nterfaceC. Both of above D. None of above53“/24”, where the /24 notation, sometimes known as a_. （ ）A. Subnet maskB. Networking addressC. Host addressD. None of above54Subnets with an 8-, _-, and 24-bit subnet addresses were know as class A, B, and C networks respectively. （ ）A. 9B. 10C. 12

25、D. 1655IPV6 has a _ bits address? （ ）A. 32B. 64C. 16D. 12856_ means that IPv6 nodes also have a complete IPv4 implementation as well? （ ）A. Dual stackB. TunnelingC. Bridge connectionD. Forwarding57_ means that IPv6 carried as payload in IPv4 data-gram among IPv4 routers? （ ）A. Dual stackB. Tunneling

26、C. Bridge connectionD. Forwarding58Typically a host is attached directly to one router, the _ for the host. （ ）A. Default routerB. Source routerC. Destination routerD. Core router59The default router of the source host is known as _.（ ）A. Default routerB. Source routerC. Destination routerD. Core ro

27、uter60The default router of the destination host is known as _. （ ）A. Default routerB. Source routerC. Destination routerD. Core router61A path between the source and destination that has beast cost is known as_. （ ）A. Least cost pathB. Shortest pathC. Largest cost pathD. None of above62The path wit

28、h the smallest number of links between the source and the destination is known as _. （ ）A. Least cost pathB. Shortest pathC. Largest cost pathD. None of above63Which of following about DV is not correct? （ ）A. IterativeB. SynchronousC. DistributedD. Self-terminating64Which of the following is not in

29、tra-AS routing protocol? （ ）A. RIPB. OSPFC. IGRPD. BGP 65RIP is a kind of _ algorithm. （ ）A. DVB. LSC. Both of aboveD. Neither of A and B66OSPF is a kind of _ algorithm. （ ）A. DVB. LSC. Both of aboveD. Neither of A and B67The router in non-backbone areas and perform only intra-AS routing is known as

30、 _. （ ）A. Internal routersB. Area border routersC. Backbone routersD. Boundary routers68_“summarize” distances to nets in own area, advertise to other Area Border routers. （ ）A. Internal routersB. Area border routersC. Backbone routersD. Boundary routers69_ runs OSPF routing limited to backbone. （ ）

31、A. Internal routersB. Area border routersC. Backbone routersD. Boundary routers70_ connect to other ASs. （ ）A. Internal routersB. Area border routersC. Backbone routersD. Boundary routers71Which of the following is an inter-autonomous system routing protocol? （ ）A. RIPB. OSPFC. IGRPD. BGP 72_means s

32、ending a packet to all other nodes in the network. （ ）A. BroadcastB. MulticastC. Any-castD. Uni-cast73A _ packet is delivered to only a subset of network nodes. （ ）A. BroadcastB. MulticastC. Any-castD. Uni-cast74Means that the switch must receive the entire packet before it can begin to transmit the

33、 first bit of the packet onto the outbound link. （ ）A. store-and-forward transmission B. FDMC. End-to-end connection D. TDM75Datagram networks and virtual-circuit networks differ in _.（ ）A. Datagram networks are circuit-switched networks, and virtual-circuit networks are packet-switched networks.B.

34、Datagram networks are packet-switched networks, and virtual-circuit networks are circuit-switched networks.C. Datagram networks use destination addresses and virtual-circuit networks use VC. Numbers to forward packets toward their destination.D. Datagram networks use VC. Numbers and virtual-circuit

35、networks use destination addresses to forward packets toward their destination.76The Internets network layer is responsible for moving network-layer packets known as _ from one host to another. （ ）A. frame B. datagram C. segment D. message77The protocols of various layers are called _. （ ）A. the pro

36、tocol stack B. TCP/IPC. ISP D. network protocol78The two important network-layer functions are _. （ ）A. multiplexing and de-multiplexing B. routing and forwardingC. lookup and forwarding D. routing and IP addressing79The virtual circuit includes three identifiable phases but _. （ ）A. setup B. data t

37、ransfer C. forwarding VC numbers D. teardown80There are some ways to accomplish the switching in the router, which one is not included? （ ）A. switching via memory B. switching via a busC. switching via hub D. switching via an interconnection81In the router, the packet queues can form at _.（ ）A. inst

38、itutional cache B. switch fabric C. input port D. routing processor82In IPV4 datagram header, which field is to ensure that datagram do not circulate forever in the network? （ ）A. type of service B. time-to-live C. header checksum D. version83Suppose one IP datagram of 5,000 bytes (20 bytes of IP he

39、ader) and it must be forwarded to a link with an MTU of 1,500 bytes, the offset and flag of the second fragment in header are _. （ ）A. 185, 0 B. 185, 1 C. 370, 1 D. 370,084Given the IP address /20, its subnet address is _. （ ）A. B. C. 55 D. 202.96.111

40、.25585If the subnet mask is , then how many bits indicate the host address? （ ）A. 20 B. 24 C. 12 D. 1686In the following four fields, which is in IPV6 header but not in IPV4? （ ）A. source address B. destination address C. version D. flow label87One host is attached directly to one route

41、r, the router is _.（ ）A. NAT router B. gateway router C. first-hop router D. interval router88The Internets network layer includes the following components but _.（ ）A. IP protocol B. the Internet Message Control ProtocolC. Routing Protocol D. Channel Partitioning Protocol89In the following protocols

42、, which one is inter-AS routing protocol? （ ）A. RIP B. OSPF C. BGP D. ICMP90In the following four descriptions about autonomous system, which one is not correct? （ ）A. An autonomous system is a collection of routers under the same administrative and technical control.B. All routers in an autonomous

43、system run the same routing protocol.C. The routing algorithm running within an autonomous system is called an intra-AS routing protocol.D. The routers that connect AS-s to each other are called default router.91In the loop of the Dijkstras algorithm, for node x, add y to N, and update the cost of y

44、s neighbor v, then D(v) is _. （ ）A. c(x, v) B. minD(v), D(x)+c(x, v) C. minD(v), D(y)+c(y, v) D. c(y, v)92Consider the data D is , if use even parity checking approach, the parity bit is ( ), if use odd parity checking approach, the parity bit is _. （ ）A. 0, 0 B. 0, 1 C. 1, 0 D. 1, 1 93The ability t

45、o determine the interfaces to which a frame should be directed, and then directing the frame to those interfaces is _.（ ）A. filtering B. forwardingC. self-learning D. optimal routing94Given that costs are assigned to various edge in the graph abstraction. In the following four descriptions, which on

46、e is not correct? （ ）A. The shortest path is the path with smallest number of links between the source and destination.B. The least cost path is not always the shortest path.C. If all edges have same cost, the least cost path must be the shortest path.D. If all edges have various costs, the least co

47、st path must not be the shortest path.95Given the IP address /20, its broadcast address is _. （ ）A. B. C. 55 D. 5596If the subnet mask is , then how many bits indicate the host address? （ ）A. 20 B. 12 C. 24 D. 1697In IPV6 datagram header, the field Next-header is equivalent to the field ( ) in IPV4. （ ）A. upper-layer protocol B. time-to-live C. header checksum D. version98For one host, its source router is also called _. （ ）A. NAT router B. gateway router C. first-hop r