计算机网络教程自顶向下方法选择题及答案-Chapt-4-Network-Layer-QUIZZ.docx

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1、Chapter 4 Network Layer.Packetizing at the network layer involvesA) Encapsulating the payload at the sourceB) Adds a header that contains the source and destination informationC) Decapsulating the payload at the destinationD) All of the choices are correct2.Routers in the path are not allowed to.A)

2、fragment the packet they receiveB) decapsulate the packetC) change source or destination addressD) All of the choices are correctl l J VH/ ABCDThe network layer in the Internet provides. comprehensive error and flow control, limited error control, but no flow control, comprehensive error control but

3、 limited flow control. All of the choices are correct4.In a virtual-circuit approach, the forwarding decision is based on the value of the field in the packet header.a)b)qd)source addressdestination addresslabelNone of the choices are correct5.In a datagram approach, the forwarding decision is based

4、 on the value of the field inthe packet header.A)B)QD)source addressdestination addresslabelNone of the choices are correct6.The performance of a network can be measured in terms of.A)B)QD)delaythroughputpacket lossall of the choices are correct7.Transmission delay (time) is the ratio of.A) transmis

5、sion rate to packet lengthB) transmission rate to distanceC) packet length to transmission rateD) processing time to transmission rate8.l ) n IHf ABCDPropagation delay (time) is the ratio of. transmission rate to propagation speed propagation speed to distance packet length to propagation speed dist

6、ance to propagation speed9.When the load in the network reaches the network capacity, the packet delay and theA)B)QD)network throughput reaches. increases sharply; its minimum increases sharply; its maximum decreases sharply; its minimum decreases sharply; its maximum10.In open-loop congestion contr

7、ol, policies are applied.A) to prevent congestion before it happensB) to alleviate congestion after it happensC) to either prevent congestion before it happens or to alleviate congestion after it happensD) None of the choices are correct11.The technique is one of the open-loop congestion policyA) ba

8、ckpressureB) choke packetC) implicit signaling- a12.heA)B)QD)13.lplA)B)QD)D) None of the choices are correct technique is one of the close-loop congestion policyacknowledgment policychoke packetdiscarding policyNone of the choices are correctp rotocol.connection-oriented unreliableconnection-oriente

9、d reliableconnectionless unreliableconnectionless reliable14.An HLEN value of decimal 10 means.A) there are 10 bytes of optionsB) there are 10 bytes in the headerC) there are 40 bytes of optionsD) there are 40 bytes in the header15.If the fragment offset has a value of 100, it means that.A) the data

10、gram has not been fragmentedB) the datagram is 100 bytes in sizeC) the first byte of the datagram is byte 800D) None of the choices are correct16.What is needed to determine the number of the last byte of a fragment?A) offset numberB) total lengthC) both offset number and the total lengthD) None of

11、the choices are correct17.The IP header size is bytes long.A) 20 to 60B) 20C) 60D) None of the choices are correct18.A)B)0D)Packets in the IP layer are called. segments datagrams frames None of the choices are correct19.The total length field defines the total length of the datagram.A) including the

12、 headerB) excluding the headerC) excluding the option lengthD) None of the choices arecorrect20.When a datagram is encapsulated in a frame, the total size of the datagram must be less than thel %)/ 1 H ABCDMUTMATMTUNone of the choices are correct21.An IPv4 address is normally represented in basein d

13、otted-decimal notation.A) 16B) 256C) 10D) None of the choices are correctinto classes.5None of the choices are correct23.The number of addresses assigned to an organization in classless addressing A) can be any numberB) must be a multiple of 256C) must be a power of 2D) None of the choices are corre

14、ct24.The first address assigned to an organization in classless addressing.A) must be evenly divisible by the number of addresses in the organizationB) must be divisible by 128C) must belong to one of the A, B, or C classesD) None of the choices are correct25lnA)B)QD)subnetting, the number of addres

15、ses in each subnet must.be a power of 2be a multiple of 128be divisible by 128None of the choices are correct26.What is the default prefix length for class A in CIDR notation?9816None of the choices are correctA)B)Q627.What is the default prefix length for class B in CIDR notation?9816None of the choices are correcta)b)qd)28.WhatA)B)Qis the default prefix length for class C in CIDR notation?24816