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1、Chapter 4 Network Layer1.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)fr
2、agment the packet they receiveB)decapsulate the packetC)change source or destination addressD)All of the choices are correct3.The network layer in the Internet provides _.A)comprehensive error and flow control.B)limited error control, but no flow control.C)comprehensive error control but limited flo
3、w control.D)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)source addressB)destination addressC)labelD)None of the choices are correct5.In a datagram approach, the forwarding decision is based on the
4、value of the _ field in the packet header.A)source addressB)destination addressC)labelD)None of the choices are correct6.The performance of a network can be measured in terms of _.A)delayB)throughputC)packet lossD)all 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.Propagation delay (time) is the ratio of _.A)transmission rate to propagation speedB)propagation speed to distanceC)packet length to propagation speedD)distance to pro
6、pagation speed9.When the load in the network reaches the network capacity, the packet delay _ and the network throughput reaches _.A)increases sharply; its minimumB)increases sharply; its maximumC)decreases sharply; its minimumD)decreases sharply; its maximum10.In open-loop congestion control, polic
7、ies 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)backpressure
8、B)choke packetC)implicit signalingD)None of the choices are correct12.The _ technique is one of the close-loop congestion policyA)acknowledgment policyB)choke packetC)discarding policyD)None of the choices are correct13.IP is a _ protocol.A)connection-oriented unreliableB)connection-oriented reliabl
9、eC)connectionless unreliableD)connectionless 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 datagram h
10、as 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 the choices a
11、re correct17.The IP header size is _ bytes long.A)20 to 60B)20C)60D)None of the choices are correct18.Packets in the IP layer are called _.A)segmentsB)datagramsC)framesD)None of the choices are correct19.The total length field defines the total length of the datagram _.A)including the headerB)exclud
12、ing the headerC)excluding the option lengthD)None of the choices are correct20.When a datagram is encapsulated in a frame, the total size of the datagram must be less than the _.A)MUTB)MATC)MTUD)None of the choices are correct21.An IPv4 address is normally represented in base _ in dotted-decimal not
13、ation.A)16B)256C)10D)None of the choices are correct22.In classful addressing, the IPv4 address space is divided into _ classes.A)3B)4C)5D)None 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)m
14、ust be a power of 2D)None of the choices are correct24.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 correct25.In subnetting, the number of addresses in each subnet must _
