天津理工大学计算机网络题库资格考试计算机等级考试资格考试计算机等级考试.pdf

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1、 PART I:Choice B 1.Which of the following services does not the transport layer provide for the application layer?A.In-order delivery of data segments between processes B.Best effort delivery of data segments between communicating hosts C.Multiplexing and demultiplexing of transport layer segments D

2、.Congestion control A 2.What are the two of the most important protocols in the Internet?A.TCP and IP B.TCP and UDP C.TCP and SMTP D.ARP and DNS C 3.The Internet provides two services to its distributed applications:a connection oriented reliable service and a().A.connection oriented unreliable serv

3、ice B.connectionless reliable service C.connectionless unreliable service D.In order data transport service D 4.Processes on two different end systems communicate with each other by exchanging()across the computer network.A.packets B.datagram C.frames D.messages A 5.The job of delivering the data in

4、 a transport-layer segment to the correct socket is called().A.demultiplexing B.multiplexing C.TDM D.FDM C 6.Two important reasons that the Internet is organized as a hierarchy of networks for the purposes of routing are:A.Least cost and maximum free circuit availability B.Message complexity and spe

5、ed of convergence C.Scale and administrative autonomy D.Link cost changes and link failure 7.Which of characters is not distance-vector algorithm s characters？()A.iterative B.global C.asynchronous D.distributed 8.The length of IPV6 address is()bits.A.32 B.48 C.64 D.128 9.The host component of a CIDR

6、 address of the forma.b.c.d/25 can contain addresses for:D.25 hosts(minus“special”hosts)C 10.The primary function of the address resolution protocol(ARP)that resides in Internet hosts and routers is:A.To provide LAN router functions B.To translate between LAN addresses and physical interface address

7、es C.To translate IP addresses to LAN addresses D.To calculate the shortest path between two nodes on a LAN A 11.The POP3 protocol runs over _ and uses port _.A.TCP 110 B.UDP 110 C.UDP 25 D.TCP 25 D 12.When a destination host transport layer receives data from the network layer,it unambiguously iden

8、tifies the appropriate process to pass the data to by using a triplet consisting of:A.225 hosts(minus special”hosts)B.512 hosts(minus special”hosts)C.2(32-25)hosts(minus spehcoiaslts)”A.Source port#,destination IP address,and source IP address B.Destination port#,source port#,process ID#C.Destinatio

9、n port#,source port#,destination IP address D.Destination port#,source port#,source IP address D 13.From the list below,select the items found in the TCP segment structurethat are not found in the UDP segment structure:A.Application Generated Data B.Destination Port#C.Source Port#D.Sequence#A 14.The

10、 RIP routing protocol is based on an algorithm that is:A.Based on information received only from link“neighbors”B.A link state algorithm C.An OSPF algorithm D.A centralized routing algorithm B 15.With an exterior routing protocol,which of the following issues generally dominates the routing decision

11、s?A.Geographical distance between AS s B.Policy C.Number of AS s traversed D.Current congestionlevels in the AS s A 1.End system are connected together by _.A.communication links B.application layer C.transport layer D.the network layer C 2.Which application s NOT using TCP?A.SMTP B.HTTP C.DNS D.All

12、 of them B 3.In the polling protocols,the master node polls each of the nodes in a/an _ fashion.A.random B.appointed C.round-robin D.uncirculated C 4.The DNS protocol runs over _ and uses port _.A.UDP 36 B.TCP 36 C.UDP 53 D.TCP 53 A 5.TCP provides a _ service to its applications to eliminate the pos

13、sibility of the sender over-flowing the receiver s buffer.A.flow-control B.congestion control C.reliability control D.data connection D 6.We can classify just about any multiple access protocol as belonging to one of three categories:channel partitioning protocols,random access protocols,and _.A.add

14、ress resolution protocols B.Dynamic host configuration protocols C.link-control protocols D.taking-turns protocols B 8.The maximum transfer unit(MTU)in Ethernet frame structure is()byte.A.1000 B.1500 C.800 D.2000 B 9.The socket of UDP is identified by _ and _.A.source IP address and source port numb

15、er B.destination IP address and destination port number.C.source IP address and destination port number.D.destination IP address and source IP address.C 10.Which is not plug and play in the following four items?A.DHCP B.Hubs C.Routers D.Switches D 11 Which of routers is not default routers?A.first-h

16、op router B.source router C.destination router D.second-hop router B 13.ICMP is _.A.the protocol of Application layer 间的数据传输网络层主机到主机的传输链路层相邻节电数据传输物理层透明传输比特流答答数据报网络是面向非连接的服务不可靠的服务没有流量控制和拥塞控制虚电路网络是面向连接的网络可以提供可靠的传输服务具有流量控制允许有数据丢失使用弹性带宽时间不敏感的地址的网络地址部分不同则处口如B.the protocol of network layer C.the protocol

17、of transport layer D.not a part of TCP/IP protocols B 14.As general,we has following channel partitioning protocols except _.A.TDM B.CSMA C.FDM D.CDMA D 15._ is most used for error reporting.A.UDP B.SMTP C.FTP D.ICMP B 16.The header of IPV6 is _ byte.A.20 B.40 C.60 D.80 B 17.In the network layer the

18、se service are host-to-host service provided by _(.B)A.the transport layer to the network layer B.the network layer to the transport layer C.the network layer to the network layer D.the transport layer to the transport layer A 18.If there is not enough memory to buffer an incoming packet,a policy th

19、at drop the arriving packet called .A.drop-tail B.packet loss C.protocol D.encapsulation C 19.In either case,a _ receives routing protocol messages,which are used to configure its forwarding table.A.server B.host C.router D.Modem D 20.Which of the following functions does not belong to PPP_.A.framin

20、g B.link-control protocols C.network-control protocols D.error correction B 1.Which of the following services does the Internet network layer provide for the Internet transport layer?A.In-order delivery of data segments between processes B.Best effort delivery of data segments between communicating

21、hosts C.Multiplexing and demultiplexing of transport layer segments D.Congestion control D 2.The main task of the Internet s Domain Name System(DNS)is to:A.Translate port numbers to IP addresses B.Specify the standards for Internet domain names C.Provide an authority for registering domain names D.T

22、ran slate mnemon ic(记忆的)n ames to IP addresses A 10.The FTP protocol runs over _ and uses port _.A.TCP 21 B.TCP 80 C.UDP 20 D.TCP 110 C 3.RDT3.0 sreceiver FSM is same to:a)RDT1.0 b)RDT2.1 c)RDT2.2 d)RDT2.0 B 4.The Transmission Control Protocol(TCP)provides which of the following services?a)End-to-en

23、d station addressing b)Application multiplexing c)Inter network routing d)Medium access control(MAC)间的数据传输网络层主机到主机的传输链路层相邻节电数据传输物理层透明传输比特流答答数据报网络是面向非连接的服务不可靠的服务没有流量控制和拥塞控制虚电路网络是面向连接的网络可以提供可靠的传输服务具有流量控制允许有数据丢失使用弹性带宽时间不敏感的地址的网络地址部分不同则处口如D 6.Give n that the requested in formatio n is not available at a

24、ny in termediate databases,a non-iterated DNS query from a requesting host would follow the path:a)Root name server,local name server,authoritative name server b)Authoritative name server,root name server,host name server c)Local name server,root name server,local name server,authoritative name serv

25、er e)Local name server,root name server,authoritative name server A 8.lect the four esse ntial steps,briefly described,for term in ati ng a TCP connection betwee n a clie nt and a a)2,3,5,6 b)5,1,2,3 c)1,3,5,7 d)2,3,4,6 B 1O.Whe n compe nsati ng for link cost cha nges in the dista nce vector algorit

26、hm,it can gen erally be said that:a)In creased costs are propagated quickly,i.e.,“bad n ews”travels fast b)Decreased costs are propagated rapidly,i.e.,“good news”travels fast c)Decreased costs do not conv erge d)None of the above B 14.As an IP datagram travels from its source to its dest in ati on:a

27、)the source IP address is changed at each router to identify the sending router b)the router uses the destination IP address to consult its routing table c)the router does not use the IP addresses in the datagram d)the destination IP address is changed at each router to reflect the next hop C 15.Fro

28、m the list below,choose the bit pattern which could be a valid generator value for the CRC code(R)11010:a)1110 b)011010 c)100101 d)10011 A 16.C on sider sen di ng a 1300 byte IPv4 datagram into a link that has an MTU of 500 bytes:a)Three fragments are created.b)Four fragme nts are created.c)Three fr

29、agme nts are created with offsets 0,500 1000 d)The last fragment consists of exactly 300 bytes of data from the original datagram C 17.Suppose one IPv6 router wants to send a datagram to ano ther IPv6 router,but the two are conn ected together via an intervening IPv4 router.If the two routers use tu

30、nneling,then:a)The sending IPv6 router creates an IPv4 datagram and puts it in the data field of an IPv6 datagram.b)The sending IPv6 router creates one or more IPv6 fragments,none of which is larger than the maximum size of an IPv4 datagram.c)The sending IPv6 router creates an IPv6 datagram and puts

31、 it in the data field of an IPv4 datagram.d)The sending IPv6 router creates an IPv6 datagram and intervening IPv4 router will reject the IPv6 datagram D 18.Which of the following was an important consideration in the design of IPv6 a)fixed len gth 40-byte header and specified opti ons to decrease pr

32、ocess ing time at IPv6 no des b)128-bit addresses to exte nd the address space server,assuming that the initiating host is the client:(6)Clie nt sends TCP segme nt with ACK0 and final seque nee nu mber Clie nt sends TCP segme nt with FIN=1 and goes into FIN_WAIT state Server sends TCP segme nt to AC

33、K the clie nt Server sends TCP segme nt with FIN=0 Server sends TCP segme nt with FIN=1 Clie nt sends TCP segme nt with to ACK server Clie nt sends TCP segme nt with FIN=0 s FIN request and enters CLOSE_WAIT state s FIN and en ters seco nd FIN WAIT state 间的数据传输网络层主机到主机的传输链路层相邻节电数据传输物理层透明传输比特流答答数据报网络

34、是面向非连接的服务不可靠的服务没有流量控制和拥塞控制虚电路网络是面向连接的网络可以提供可靠的传输服务具有流量控制允许有数据丢失使用弹性带宽时间不敏感的地址的网络地址部分不同则处口如c)differe nt types of service(flows)defi ned d)all of the above D 19.A n etwork bridge table is used to perform the followi ng:a)Mapp ing MAC addresses to bridge port nu mbers b)Forward ing frames directly to o

35、utbo und ports for MAC addresses it han dles c)Filteri ng(discard ing)frames that are not desti ned for MAC addresses it han dles d)All of the above PART II:True/False(1 points per questio-total:20 points)1.The DNS server can update the records.(T)2.The TCP connection is a direct virtual pipe betwee

36、n the client s socket and the server(T)3.SMTP protocol connect the sender s mail server and receiver smail server 4.Whereas a tran sport-layer protocol provides logical com muni cati on betwee n processes running on differe nt hosts,a n etwork-layer protocol provides logical com muni catio n betwee

37、n hosts.(T)5.UDP and TCP also provide in tegrity check ing by in clud ing right-detect ion fields in their headers.(F)6.If the applicati on developer chooses UDP in stead of TCP,the n the applicati on is not directly talki ng with IP.(F)7.Whe n we develop a new applicatio n,we must assig n the appli

38、catio n a port nu mber.(T)8.Real-tine applications,like Internet phone and video conferencing,react very poorly to TCP con trol.(T)9.The sen der knows that a received ACK or NAK packet was gen erated in resp onse to its most rece ntly tran smitted data packet.(T)10.To simplify term ino logy,whe n in

39、 an Internet con text,we refer to the 4-PDU as a un it.(F)11.DV algorithm is esse ntially the only routi ng algorithm used in practice today in the In terne。(F)12.Every router hasmany forwarding tables(F)13.ln either case,aserver receives routi ng protocol messages,which are used to con figure its f

40、orwardi ng table.(F)14.Among the ASs,they run the same in ter_AS rout ing protocol.T 15.Routing protocols job is to determine the path take by a datagram between source and destination.T 16.OSPF was one of the earliest intra_AS Internet routing protocols.F 17.The IPV6 datagrams are more simpler,more

41、 streamlined.(T)18.Forwarding tables in datagram networks can be modified at any time.T)19.In a VC network,the networks routers must maintain connection state information for the ongoing connections.(T)20.The routers of datagram n etworks use forwardi ng table,the routers of virtual-circuit n etwork

42、s don use forwarding table.(F)PART I:Briefly answer the following questions 1.In the“10BaseT”,T stands for).(twisted pair)2.()and()are two of the most important protocols in the internet.(TCP)(JP)3.In a client-server architecture,there is an always-on host,called the(),which services requests from m

43、any other hosts,called().(server)(clients)4.The broadcast desti nation IP address is().(255.255.255.255)5.Two of the more important()protocols are polling protocols and token-passing protocol.间的数据传输网络层主机到主机的传输链路层相邻节电数据传输物理层透明传输比特流答答数据报网络是面向非连接的服务不可靠的服务没有流量控制和拥塞控制虚电路网络是面向连接的网络可以提供可靠的传输服务具有流量控制允许有数据丢失

44、使用弹性带宽时间不敏感的地址的网络地址部分不同则处口如(taking-turns)6.Tran sport-layer protocols are impleme nted in the(),but n ot in n etwork router.(end system)7.The port nu mbers ranging()are called well-k nown port nu mbers.(0 1023)8.The()algorithm is used in many routing protocols in practices,including the Internet RIP

45、 and BGP,Novell IPX,and the original ARPAnet.(DV/distance-vector 9.I nternet con sists of hierarchy of in terc onn ected().(ISPs)10.In MAC address,broadcast address is().(FF-FF-FF-FF-FF-FF)11.AS is a collection of()under the same administrative and technical control.(routers)12.()and FDM are two tec

46、hniques that can be used to partition a broadcast channel bandwidth among all no des shari ng that cha nn el.(TDM)13.As the queues grow large,the router s buffer space will eve ntually be exhausted and()packet loss will occur.(packet loss)14.The role of the n etwork layer is to move()from a sending

47、host to a recei ving host.(packets)15.()refers to the router-local acti on of tran sferri ng a packet from an in put link in terface to the appropriate output link in terface.(Forwarding)16.The Internet n etwork layer provides asi ngle service,k nown as().(best-effort service)17.The un its of data e

48、xcha nged by a lin k-layer protocol are called().(frames)18.The()-layer protocol defi nes the format of the packets excha nged betwee n the no des at the ends of the link,as well as the actions take n by these no des whe n the packets are sent and received.(link)1.(3points)What is the difference bet

49、ween a host and end system?List the types of end systems.Is a W Server an end system?答：There is no dfferenee.Throughout this text,the words“host”and“end system”are used in tercha ngeably.End systems in clude PCs,workstati ons,Web servers,mail servers,Intern et-c onn ected PDAs,WebTVs,etc.1.(1points)

50、Why is there a Web cache?答：减少接入网络的流量、减小延迟 2.(3points)Please briefly describe the function of the five layers in TCP/IP architecture(NOTE:include the protocol data unit)答：1.应用层，提供各种网络应用，运行网络应用程序。Message 2.运输层，提供端到端进程之间的数据传输。Segme n。3.网络层，主机到主机的传输。Datagram 4.链路层，相邻节电数据传输，frame 5.物理层，透明传输比特流，bit stream