Chapter 5 The Link Layer and Local Area Network

1．A ( ) protocol is used to move a datagram over an individual link. A application-layer B transport-layer C network-layer D link-layer

2．The units of data exchanged by a link-layer protocol are called ( ). A datagrams B frames

C segments D messages

3．Which of the following protocols is not a link-layer protocol? ( ) A Ethernet B PPP C HDLC D IP

4．In the following four descriptions, which one is not correct? ( )

A link-layer protocol has the node-to-node job of moving network-layer datagrams over a single link in the path.

B The services provided by the link-layer protocols may be different.

C A datagram must be handled by the same link-layer protocols on the different links in the path.

D The actions taken by a link-layer protocol when sending and receiving frames include error detection, flow control and random access.

5．Which of the following services can not offered by a link-layer protocol? ( ) A congestion control B Link Access C Error control D Framing

6．( ) protocol serves to coordinate the frame transmissions of the many nodes when multiple nodes share a single broadcast link. A ARP B MAC C ICMP D DNS

7．In the following four descriptions about the adapter, which one is not correct? ( ) A The adapter is also called as NIC.

B The adapter is a semi-autonomous unit.

C The main components of an adapter are bus interface and the link interface. D The adapter can provide all the link-layer services.

8．Consider CRC error checking approach, the four bit generator G is 1011, and suppose that the data D is 10101010, then the value of R is( ). A 010 B 100

C 011 D 110

9．In the following four descriptions about random access protocol, which one is not correct? ( )

A In slotted ALOHA, nodes can transmit at random time.

B In pure ALOHA, if a frame experiences a collision, the node will immediately retransmit it with probability p.

C The maximum efficiency of a slotted ALOHA is higher than a pure ALOHA. D In CSMA/CD, one node listens to the channel before transmitting.

10．In the following descriptions about MAC address, which one is not correct? ( ) A The MAC address is the address of one node’s adapter. B No two adapters have the same MAC address.

C The MAC address doesn’t change no matter where the adapter goes. D MAC address has a hierarchical structure.

11．The ARP protocol can translate ( ) into ( ). ( ) A host name, IP address B host name, MAC address

C IP address, MAC address D broadcast address, IP address

12．The value of Preamble field in Ethernet frame structure is ( ) A 10101010 10101010……10101010 11111111 B 10101011 10101011……10101011 10101011 C 10101010 10101010……10101010 10101011 D 10101010 10101010……10101010 10101010

13．There are four steps in DHCP, the DHCP server can complete ( ). A DHCP server discovery B DHCP server offers

C DHCP request D DHCP response 14．In CSMA/CD, the adapter waits some time and then returns to sensing the channel. In the following four times, which one is impossible? ( ) A 0 bit times B 512 bit times

C 1024 bit times D 1028 bit times

15．The most common Ethernet technologies are 10BaseT and 100BaseT. “10” and “100” indicate( ).

A the maximum length between two adapters B the minimum length between two adapters C the transmission rate of the channel D the transmission rate of the node

16．The principal components of PPP include but not( ). A framing B physical-control protocol

C link-layer protocol D network-layer protocol

17．In the following four options, which service can not be provided by switch? ( ) A filtering B self-learning

C forwarding D optimal routing

18．In the following four services, which one was be required in PPP? ( ) A packet framing B error detection

C error correction D multiple types of link

19．The ability to determine the interfaces to which a frame should be directed, and then directing the frame to those interfaces is( ). A filtering B forwarding

C self-learning D optimal routing

20．In ( ) transmission(s), the nodes at both ends of a link may transmit packets at the same time. A full-duplex B half-duplex

C single-duplex D both full-duplex and half-duplex

21．Consider the data D is 01110010001, if use even parity checking approach, the parity bit is( ① ), if use odd parity checking approach, the parity bit is( ② ). ( ) A ①0 ②1 B ①0 ②0 C ①1 ②1 D ①1 ②0

22．In the following four descriptions about parity checks, which one is correct? ( ) A Single-bit parity can detect all errors. B Single-bit parity can correct one errors.

C Two-dimensional parity not only can detect a single bit error, but also can correct that error.

D Two-dimensional parity not only can detect any combination of two errors, but also can correct them.

23．MAC address is ( ) bits long. A 32 B 48 C 128 D 64

24．Wireless LAN using protocol ( ). A IEEE 802.3

B IEEE 802.4 C IEEE 802.5 D IEEE 802.11

25．The following protocols are belonging to multiple access protocols except for ( ).

A channel partitioning protocols B routing protocols

C random access protocols D taking-turns protocols

26．Which of the following is not belonging to channel partitioning protocols? ( ) A CSMA B FDM C CDMA D TDM

27．In the following four descriptions about CSMA/CD, which one is not correct? ( )

A A node listens to the channel before transmitting.

B If someone else begins talking at the same time, stop talking. C A transmitting node listens to the channel while it is transmitting. D With CSMA/CD, the collisions can be avoided completely.

28．( ) provides a mechanism for nodes to translate IP addresses to link-layer address. A IP B ARP C RARP D DNS

29．A MAC address is a ( )address. A physical-layer B application-layer C link-layer D network-layer

30．Which of the following is correct? ( )

A No two adapters have the same MAC address. B MAC broadcast address is FF-FF-FF-FF-FF-FF.

C A portable computer with an Ethernet card always has the same MAC address, no matter where the computer goes. D All of the above

31．In the following four descriptions, which one is not correct? ( ) A ARP resolves an IP address to a MAC address. B DNS resolves hostnames to IP addresses.

C DNS resolves hostnames for hosts anywhere in the Internet. D ARP resolves IP addresses for nodes anywhere in the Internet.

32．In the LAN, ( )protocol dynamically assign IP addresses to hosts. A DNS

B ARP C DHCP D IP

33．DHCP protocol is a four-step process: ①DHCP request. ②DHCP ACK. ③DHCP server discovery. ④DHCP server offer(s). The correct sequence is ( ) A ①②③④ B ③②①④ C ③④①② D ①④③②

34．In the Ethernet frame structure, the CRC field is ( )bytes. A 2 B 4 C 8 D 32

35．In the Ethernet frame structure, the Data field carries the ( ). A IP datagram B segment C frame D message

36．In the following four descriptions, which one is not correct? ( ) A Ethernet uses baseband transmission.

B All of the Ethernet technologies provide connection-oriented reliable service to the network layer.

C The Ethernet 10Base2 technology uses a thin coaxial cable for the bus. D The Ethernet 10BaseT technology uses a star topology. 37．Ethernet’s multiple access protocol is ( ). A CDMA B CSMA/CD C slotted ALOHA D token-passing protocol

38．In the following four descriptions about CSMA/CD, which one is not correct? ( )

A An adapter may begin to transmit at any time.

B An adapter never transmits a frame when it senses that some other adapter is transmitting.

C A transmitting adapter aborts its transmission as soon as it detects that another adapter is also transmitting.

D An adapter retransmits when it detects a collision.

39．Which of the following descriptions about CSMA/CD is correct? ( ) A No slots are used. B It uses carrier sensing. C It uses collision detection. D All of the above.

40．The Ethernet 10BaseT technology uses( )as its physical media.

A fiber optics B twisted-pair copper wire C coaxial cable D satellite radio channel

41．For 10BaseT, the maximum length of the connection between an adapter and the hub is ( )meters. A 100 B 200 C 500 D 10

42．A ( )is a physical-layer device that acts on individual bits rather than on frames. A switch B hub C router D gateway

43．A hub is a ( )device that acts on individual bits rather than on frames. A physical-layer B link-layer

C network-layer D ransport-layer

44．A switch is a( )device that acts on frame. A physical-layer B link-layer

C network-layer D transport-layer

45．In the following four descriptions, which one is not correct? ( ) A Switches can interconnect different LAN technologies. B Hubs can interconnect different LAN technologies.

C There is no limit to how large a LAN can be when switches are used to interconnect LAN segments.

D There is restriction on the maximum allowable number of nodes in a collision domain when hubs are used to interconnect LAN segments. 46．The ability to determine whether a frame should be forwarded to some interface or should just be dropped is ( ).

A filtering B forwarding

C self-learning D optimal routing

47．Which of the following devices is not a plug and play device? ( ) A hub B router C switch D repeater

48．Which of the following devices is not cut-through device? ( )

A hub B router C switch D repeater

49．In the following four descriptions, which one is not correct? ( ) A Switches do not offer any protection against broadcast storms.

B Routers provide firewall protection against layer-2 broadcast storms. C Both switches and routers are plug and play devices.

D A router is a layer-3 packet switch, a switch is a layer-2 packet switch. 50．Which device has the same collision domain? ( ) A Hub B Switch

C Router D Bridge

51．IEEE802.2 protocol belong to ( )layer A network B MAC

C LLC D physical

52．IEEE802.11 protocol defines ( )rules. A Ethernet Bus B wireless WAN C wireless LAN D Token Bus

53．In data link-layer, which protocol is used to share bandwidth? ( ) A SMTP B ICMP C ARP D CSMA/CD

54．When two or more nodes on the LAN segments transmit at the same time, there will be a collision and all of the transmitting nodes well enter exponential back-off, that is all of the LAN segments belong to the same( ). A collision domain B switch C bridge D hub 55．( )allows different nodes to transmit simultaneously and yet have their respective receivers correctly receive a sender’s encoded data bits. A CDMA B CSMA

C CSMA/CD D CSMA/CA

56．Because there are both network-layer addresses (for example, Internet IP addresses) and link-layer addresses (that is, LAN addresses), there is a need to

translate between them. For the Internet, this is the job of ( ). A RIP B OSPF C ARP D IP

57．PPP defines a special control escape byte, ( ). If the flag sequence, 01111110 appears anywhere in the frame, except in the flag field, PPP precedes that instance of the flag pattern with the control escape byte. A 01111110 B 01111101 C 10011001 D 10111110

58．The device ( ) can isolate collision domains for each of the LAN segment. A modem B switch C hub D NIC

59．In the following four descriptions about PPP, which one is not correct? ( ) A PPP is required to detect and correct errors.

B PPP is not required to deliver frames to the link receiver in the same order in which they were sent by the link sender.

C PPP need only operate over links that have a single sender and a single receiver. D PPP is not required to provide flow control.

60．In the PPP data frame, the( ) field tells the PPP receivers the upper-layer protocol to which the received encapsulated data belongs. A flag B control C protocol D checksum

61．PPP’s link-control protocols (LCP) accomplish ( ). A initializing the PPP link B maintaining the PPP link C taking down the PPP link D all of the above

62．The PPP link always begins in the ( ) state and ends in the ( ) state. ( ) A open, terminating B open, dead C dead, dead D dead, terminating

63．For( ) links that have a single sender at one end of the link and a single receiver at the other end of the link. A point-to-point B broadcast C multicast

D all of the above 64．With ( )transmission, the nodes at both ends of a link may transmit packets at the same time.

A half-duplex B full-duplex

C simplex(单工) D synchronous 65．With ( ) transmission, a node can not both transmit and receive at the same time. A half-duplex B full-duplex

C simplex(单工) D synchronous

66．Which of the following functions can’t be implemented in the NIC? ( ) A encapsulation and decapsulation B error detection

C multiple access protocol D routing

67．Which of the following four descriptions is wrong? ( )

A The bus interface of an adapter is responsible for communication with the adapter’s parent node.

B The link interface of an adapter is responsible for implementing the link-layer protocol.

C The bus interface may provide error detection, random access functions.

D The main components of an adapter are the bus interface and the link interface. 68．For odd parity schemes, which of the following is correct? ( ) A 011010001 B 111000110 C 110101110 D 000110110

69．( )divides time into time frames and further divides each time frame into N time slots.

A FDM B TMD C CDMA D CSMA

70．With CDMA, each node is assigned a different ( ) A code B time slot C frequency D link

71．Which of the following four descriptions about random access protocol is not correct? ( )

A A transmission node transmits at the full rate of the channel

B When a collision happens, each node involved in the collision retransmits at once.

C Both slotted ALOHA and CSMA/CD are random access protocols. D With random access protocol, there may be empty slots.

72．PPP defines a special control escape byte 01111101. If the data is b1b201111110b3b4b5, the value is( )after byte stuffing. A b1b20111110101111110b3b4b5 B b1b20111111001111101b3b4b5 C b5b4b30111111001111101b2b1 D b5b4b30111110101111110b2b1

73．MAC address is in ( ) of the computer. A RAM B NIC C hard disk D cache

74．Which of the following is wrong? ( )

A ARP table is configured by a system administrator B ARP table is built automatically C ARP table is dynamic

D ARP table maps IP addresses to MAC addresses 75．NIC works in ( )layer. A physical B link C network D transport

76．In LAN, if UTP is used, the common connector is( ). A AUI B BNC C RJ-45 D NNI

77．The modem’s function(s) is(are) ( ). A translates digital signal into analog signal B translates analog signal into digital signal

C both translates analog signal into digital signal and translates digital signal into analog signal

D translates one kind of digital signal into another digital signal 78．( )defines Token-Ring protocol. A IEEE 802.3 B IEEE 802.4 C IEEE 802.5 D IEEE 802.2

79．( )defines Token-Bus protocol. A IEEE 802.3 B IEEE 802.4 C IEEE 802.5 D IEEE 802.2

80．( ) defines CSMA/CD protocol. A IEEE 802.3 B IEEE 802.4 C IEEE 802.5 D IEEE 802.2

81．The computer network that concentrated in a geographical area, such as in a building or on a university campus, is ( ) A a LAN B a MAN C a WAN D the Internet

82．The MAC address is ( ) bits long. A 32 B 48 C 128 D 256

83．Which of the following four descriptions about MAC addresses is wrong? ( ) A a MAC address is burned into the adapter’s ROM B No two adapters have the same address C An adapter’s MAC address is dynamic D A MAC address is a link-layer address

84．Which of the following four descriptions about DHCP is correct? ( ) A DHCP is C/S architecture

B DHCP uses TCP as its underlying transport protocol C The IP address offered by a DHCP server is valid forever

D The DHCP server will offer the same IP address to a host when the host requests an IP address

85． The ( )field permits Ethernet to multiplex network-layer protocols. A preamble B type C CRC

D destination MAC address

86．For 10BaseT, the maximum length of the connection between an adapter and the hub is ( ) meters. A 50 B 100 C 200 D 500

87．An entry in the switch table contains the following information excepts for ( ) A the MAC address of a node

B the switch interface that leads towards the node

C the time at which the entry for the node was placed in the table D the IP address of a node

88．Consider the 4-bit generator , G is 1001, and suppose that D has the value 101110000. What is the value of R?

89．Consider the following graph of the network. Suppose Host A will send a datagram to Host B, Host A run OICQ on port 4000, Host B run OICQ on port 8000. All of ARP tables are up to date. Enumerate all the steps when message “Hello” is sent from host A to host B.