【计算机类职业资格】网络工程师-计算机专业英语(三)及答案解析.doc

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1、网络工程师-计算机专业英语(三)及答案解析(总分：50.00，做题时间：90 分钟)一、单项选择题(总题数：10，分数：50.00)Although a given waveform may contain frequencies over a very broad range, as a practical matter any transmission system will be able to accommodate only a limited band of (86) . This, in turn, limits the data rate that can be carried

2、 on the transmission (87) A square wave has an infinite number of frequency components and hence an infinite (88) However, the peak amplitude of the kth frequency component, kf, is only l/k, so most of the (89) in this waveform is in the first few frequency components. In general, any digital wavefo

3、rm will have (90) bandwidth. If we attempt to transmit this waveform as a signal over any medium, the transmission system will limit the bandwidth that can be transmitted.（分数：5.00）(1).A. frequencies B. connections C. diagrams D. resources（分数：1.00）A.B.C.D.(2).A. procedure B. function C. route D. medi

4、um（分数：1.00）A.B.C.D.(3).A. source B. bandwidth C. energy D. cost（分数：1.00）A.B.C.D.(4).A. frequency B. energy C. amplitude D. phase（分数：1.00）A.B.C.D.(5).A. small B. limited C. infinite D. finite（分数：1.00）A.B.C.D.Melissa and LoveLetter made use of the trust that exists between friends or colleagues. Imagi

5、ne receiving an (46) from a friend who asks you to open it. This is what happens with Melissa and several other similar E-mail (47) . Upon running, such worms usually proceed to send themselves out to email addresses from the victims address book, previous emails, web pages (48) .As administrators s

6、eek to block dangerous email attachments through the recognition of well-known (49) , virus writers use other extensions to circumvent such protection. Executable (.exe)files are renamed to. bat and. cmd plus a whole list of other extensions and will still run and successfully infect target users.Fr

7、equently, hackers try to penetrate networks by sending an attachment that looks like a flash movie, which, while displaying some cute animation, simultaneously runs commands in the background to steal your passwords and give the (50) access to your network.（分数：5.00）(1).A. attachment B. packet C. dat

8、agram D. message（分数：1.00）A.B.C.D.(2).A. virtual B. virus C. worms D. bacteria（分数：1.00）A.B.C.D.(3).A. memory B. caches C. ports D. registers（分数：1.00）A.B.C.D.(4).A. names B. cookies C. software D. extensions（分数：1.00）A.B.C.D.(5).A. cracker B. user C. customer D. client（分数：1.00）A.B.C.D.Routing protocols

9、 use different techniques for assigning (81) to individual networks. Further, each routing protocol forms a metric aggregation in a different way. Most routing protocols can use multiple paths if the paths have an equal (82) . Some routing protocols can even use multiple paths when paths have an une

10、qual cost. In either case, load (83) can improve overall allocation of network bandwidth. When multiple paths are used, there are several ways to distribute the packets. The two most common mechanisms are per-packet load balancing and per-destination load balancing. Per-packet load balancing distrib

11、utes the (84) across the possible routes in a manner proportional to the route metrics. Per-destination load balancing distributes packets across the possible routes based on (85) .（分数：5.00）(1).A. calls B. metrics C. links D. destinations（分数：1.00）A.B.C.D.(2).A. user B. distance C. entity D. cost（分数：

12、1.00）A.B.C.D.(3).A. bracketing B. balancing C. downloading D. transmitting（分数：1.00）A.B.C.D.(4).A. destinations B. resources C. packets D. sources（分数：1.00）A.B.C.D.(5).A. destinations B. resources C. packets D. Sources（分数：1.00）A.B.C.D.NACs (Network Access Control) role is to restrict network access to

13、 only compliant endpoints and (66) users. However, NAC is not a complete LAN (67) solution; additional proactive and (68) security measures must be implemented. Nevis is the first and only comprehensive LAN security solution that combines deep security processing of every packet at 100Gbps, ensuring

14、 a high level of security plus application availability and performance. Nevis integrates NAC as the first line of LAN security (69) In addition to NAC, enterprises need to implement role-based network access control as well as critical proactive security measures-real-time, multilevel (70) inspecti

15、on and microsecond threat containment.（分数：5.00）(1).A. automated B. distinguished C. authenticated D. destructed（分数：1.00）A.B.C.D.(2).A. crisis B. security C. favorable D. excellent（分数：1.00）A.B.C.D.(3).A. constructive B. reductive C. reactive D. productive（分数：1.00）A.B.C.D.(4).A. defense B. intrusion C

16、. inbreak D. protection（分数：1.00）A.B.C.D.(5).A. port B. connection C. threat D. insurance（分数：1.00）A.B.C.D.DOM is a platform-and language- (41) API that allows programs and scripts to dynamically access and update the content, structure and style of WWW documents (currently, definitions for HTML and X

17、ML documents are part of the specification). The document can be further processed and the results of that processing can be incorporated back into the presented (42) . DOM is a (43) -based API to documents, which requires the whole document to be represented in (44) while processing it. A simpler a

18、lternative to DOM is the event -based SAX, which can be used to process very large. (45) documents that do not fit info the memory available for processing.（分数：5.00）(1).A. specific B. neutral C. contained D. related（分数：1.00）A.B.C.D.(2).A. text B. image C. page D. graphic（分数：1.00）A.B.C.D.(3).A. table

19、 B. tree C. control D. event（分数：1.00）A.B.C.D.(4).A. document B. processor C. disc D. memory（分数：1.00）A.B.C.D.(5).A. XML B. HTML C. script D. web（分数：1.00）A.B.C.D.Border Gateway Protocol(BGP) is inter-autonomous system (96) protocol. BGP is based on a routing method called path vector routing. Distance

20、 vector routing is not a good candidate for inter-autonomous system routing because there are occasions on which the route with the smallest (97) count is not the preferred route. For example, we may not want a packet through an not secure even though it is the shortest route. Also, distance vector

21、routing is unstable due to the fact that the routers announce only the number of hop counts to the destination without actually defining the path that leads to that (98) . A router that receives a distance vector advertisement packet may be fooled if the shortest path is actually calculated through

22、the receiving router itself. Link (99) routing is also not a good candidate for inter-autonomous system routing because an Internet is usually too big for this routing method. To use link state routing for the whole internet would require each router to have a huge link state database. It would also

23、 take a long time for each router to calculate its rousting (100) using the Dijkstra algorism.（分数：5.00）(1).A. routing B. switching C. transmitting D. receiving（分数：1.00）A.B.C.D.(2).A. path B. hop C. route D. packet（分数：1.00）A.B.C.D.(3).A. connection B. window C. source D. destination（分数：1.00）A.B.C.D.(

24、4).A. status B. search C. state D. research（分数：1.00）A.B.C.D.(5).A. table B. state C. metric D. cost（分数：1.00）A.B.C.D.The Border Gateway Protocol (BGP) is an interautonomous system (76) protocol. The primary function of a BGP speaking system is to exchange network (77) information with other BGP syste

25、m. This network reachability information includes information on the list of Autonomous System (ASs) that reachability information traverses. BGP-4 provides a new set of mechanisms for supporting (78) interdomain routing. These mechanisms include support for advertising an IP (79) and eliminate the

26、concept of network class within BGR BGP-4 also introduces mechanisms that allow aggregation of routes, including. (80) of AS paths. These changes provide support for the proposed supernettting scheme.（分数：5.00）(1).A. secubility B. reachability C. capability D. reliability（分数：1.00）A.B.C.D.(2).A. answe

27、rless B. connectionless C. confirmless D. classless（分数：1.00）A.B.C.D.(3).A. prefix B. suffix C. infix D. reflex（分数：1.00）A.B.C.D.(4).A. reservation B. relation C. aggregation D. connection（分数：1.00）A.B.C.D.(5).A. connecting B. resolving C. routing D. supernettting（分数：1.00）A.B.C.D.In the following essay

28、, each blank has four choices. Choose the best answer and writedown on the answer sheet.Microwave communication uses high-frequency (26) waves that travel in straightlines through the air. Because the waves cannot (27) with the curvature of the earth, they can be (28) only over short distance. Thus,

29、 microwave is a good (29) for sendingdata between buildings in a city or on a large college campus. For longer distances, the wavesmust be relayed by means of “dishes“ or (30) . These can be installed on towers, highbuildings, and mountain tops.（分数：5.00）(1).A. optical B. radio C. electrical D. magne

30、tic（分数：1.00）A.B.C.D.(2).A. reflex B. distort C. bend D. absorb（分数：1.00）A.B.C.D.(3).A. transmitted B. transformed C. converted D. delivered（分数：1.00）A.B.C.D.(4).A. material B. equipment C. medium D. channel（分数：1.00）A.B.C.D.(5).A. repeaters B. radars C. telephones D. antennas（分数：1.00）A.B.C.D.For each b

31、lank, choose the best answer from the four choices and write down on the answer sheet.(21) is a six bytes OSI layer 2 address which is burned into every networking device that provides its unique identity for point to point communication.(22) is a professional organization of individuals in multiple

32、 professions which focuses on effort on lower-layer protocols.(23) functions with two layers of protocols. It can connect networks of different speeds and can be adapted to an environment as it expands.(24) is the popular LAN developed under the direction of the IEEE802.5.(25) is the popular backbon

33、e technology for transmitting information at high speed with a high level of fault tolerance which is developed under the direction of ANSI.（分数：5.00）(1).A. The MAC address B. The IP addressC. The subnet address D. The virtual address（分数：1.00）A.B.C.D.(2).A. ISO B. ANSI C. CCYIT D. IEEE（分数：1.00）A.B.C.

34、D.(3).A. The hub B. The bridge C. The router D. The proxy（分数：1.00）A.B.C.D.(4).A. Ethernet B. Token Bus C. Token Ring D. DQDB（分数：1.00）A.B.C.D.(5).A.X.25 B. ATM C. FDDI D. SMDS（分数：1.00）A.B.C.D.Traditional Internet access methods like dial-up were so slow that host computers were connected to the dial-

35、up. (6) at the customer premise over slow (7) ports. PPP was designed to run directly over these serial links. But with the advent of broadband Internet (8) technologies such as ADSL and cable modems there has been a considerable increase in the bandwidth delivered to the end users. This means that

36、the host computers at the customer premise connect to the (9) or cable “modem“ over a much faster medium such as Ethernet. It also means that multiple (10) can connect to the Internet through the same connection.（分数：5.00）(1).A. buffer B. modem C. computer D. server（分数：1.00）A.B.C.D.(2).A. parallel B.

37、 digital C. serial D. variable（分数：1.00）A.B.C.D.(3).A. access B. cache C. cast D. storage（分数：1.00）A.B.C.D.(4).A. FDDI B. HDSL C. ADSL D. CDMA（分数：1.00）A.B.C.D.(5).A. cables B. hosts C. servers D. modems（分数：1.00）A.B.C.D.网络工程师-计算机专业英语(三)答案解析(总分：50.00，做题时间：90 分钟)一、单项选择题(总题数：10，分数：50.00)Although a given w

38、aveform may contain frequencies over a very broad range, as a practical matter any transmission system will be able to accommodate only a limited band of (86) . This, in turn, limits the data rate that can be carried on the transmission (87) A square wave has an infinite number of frequency componen

39、ts and hence an infinite (88) However, the peak amplitude of the kth frequency component, kf, is only l/k, so most of the (89) in this waveform is in the first few frequency components. In general, any digital waveform will have (90) bandwidth. If we attempt to transmit this waveform as a signal ove

40、r any medium, the transmission system will limit the bandwidth that can be transmitted.（分数：5.00）(1).A. frequencies B. connections C. diagrams D. resources（分数：1.00）A. B.C.D.解析：(2).A. procedure B. function C. route D. medium（分数：1.00）A.B.C.D. 解析：(3).A. source B. bandwidth C. energy D. cost（分数：1.00）A.B.

41、 C.D.解析：(4).A. frequency B. energy C. amplitude D. phase（分数：1.00）A.B. C.D.解析：(5).A. small B. limited C. infinite D. finite（分数：1.00）A.B.C. D.解析：Melissa and LoveLetter made use of the trust that exists between friends or colleagues. Imagine receiving an (46) from a friend who asks you to open it. This

42、 is what happens with Melissa and several other similar E-mail (47) . Upon running, such worms usually proceed to send themselves out to email addresses from the victims address book, previous emails, web pages (48) .As administrators seek to block dangerous email attachments through the recognition

43、 of well-known (49) , virus writers use other extensions to circumvent such protection. Executable (.exe)files are renamed to. bat and. cmd plus a whole list of other extensions and will still run and successfully infect target users.Frequently, hackers try to penetrate networks by sending an attach

44、ment that looks like a flash movie, which, while displaying some cute animation, simultaneously runs commands in the background to steal your passwords and give the (50) access to your network.（分数：5.00）(1).A. attachment B. packet C. datagram D. message（分数：1.00）A. B.C.D.解析：(2).A. virtual B. virus C.

45、worms D. bacteria（分数：1.00）A.B.C. D.解析：(3).A. memory B. caches C. ports D. registers（分数：1.00）A.B. C.D.解析：(4).A. names B. cookies C. software D. extensions（分数：1.00）A.B.C.D. 解析：(5).A. cracker B. user C. customer D. client（分数：1.00）A. B.C.D.解析：Routing protocols use different techniques for assigning (81)

46、 to individual networks. Further, each routing protocol forms a metric aggregation in a different way. Most routing protocols can use multiple paths if the paths have an equal (82) . Some routing protocols can even use multiple paths when paths have an unequal cost. In either case, load (83) can imp

47、rove overall allocation of network bandwidth. When multiple paths are used, there are several ways to distribute the packets. The two most common mechanisms are per-packet load balancing and per-destination load balancing. Per-packet load balancing distributes the (84) across the possible routes in

48、a manner proportional to the route metrics. Per-destination load balancing distributes packets across the possible routes based on (85) .（分数：5.00）(1).A. calls B. metrics C. links D. destinations（分数：1.00）A.B. C.D.解析：(2).A. user B. distance C. entity D. cost（分数：1.00）A.B.C.D. 解析：(3).A. bracketing B. ba

49、lancing C. downloading D. transmitting（分数：1.00）A.B. C.D.解析：(4).A. destinations B. resources C. packets D. sources（分数：1.00）A.B.C. D.解析：(5).A. destinations B. resources C. packets D. Sources（分数：1.00）A. B.C.D.解析：NACs (Network Access Control) role is to restrict network access to only compliant endpoints and (66) users. However, NAC is not a complete LAN (67) solution; additional proactive and (68) security measures must be implemented. Nevis is the first and only comprehensive LAN security solution that combines deep security processing of every packet at 100Gbps, ensuring a hi