SAMPLE TEST from past EXAMS Exam3 Chapters: 14, 19, 21, 23, 24. Type of questions: multiple choices, Fill in the gaps, short answer questions YOU MUST BRING SCANTRON sheets for the multiple choices (4.5 x 11 ) (also available in the Book Store) SAMPLE TEST from past EXAMS ------------------------------------------------------------------------------------------------------------------- (This is only a sample collected from past exams to use as a guide. This semester the questions may include fill in the blanks and different nature of questions, but mostly from the text book.) ------------------------------------------------------------------------------------------------------------------- NAME: (Exam :SECTION A) Notes: Any script without a name will receive no points. You must show the calculations for the descriptive questions. 1. a. What is the type of switch shown in the following figure? b. Calculate the number of cross points required in this switch. c. What are the two popular approaches of packet switching? Discuss with examples and figures. d. Define the terms: SVC, PVC, Blocking, Message Switching. e. Complete the following table to compare a circuit switched network with a packet-switched network. Issue Circuit-Switched Packet-Switched Dedicated Path Store and Forward Need for connection Establishment Routing Table Delay f. Complete the following table to compare a PVC to an SVC connection. Issue PVC SVC Connection and disconnection Payment Table lookup Duration of an entry in a table g. Complete the following table to compare a Datagram approach to a virtual circuit approach of a packetswitching network. Issue Datagram Virtual Circuit All packets follow the same route Table look up Connection Establishment Packet may arrive out of order 1
2. Show the output of the ATM multiplexer in the following figure. 3. a.how many virtual connections are defined in a UNI interface? How many virtual interfaces are defined in an NNI interface? b. What are the categories of quality of services in ATM. Define the following QOS terminologies with examples: SCR, PCR, MCR, CVDT, CLR, CTD and CDV and CER. c. Explain with examples the service classes used in ATM and the type of customers each serves. (CBR, VBR, ABR, UBR) d. Describe the format of an ATM cell. What is the relationship between TPs, VPs and VCs? e. How are ATM cells multiplexed? Why is multiplexing more efficient if all data units are the same size? f. Name the ATM layers and their functions. 4. a. In routing, what does the term shortest mean? b. What is the difference between a simple bridge and a transparent (learning) bridge? c. What is the function of a router? How does a router differ from a bridge? d. What is the function of a gateway? Explain with examples. 5. a. What are the 3 main elements of link state routing? b. What are the 3 main elements of distance vector routing? c. What algorithm does link state routing use to calculate the routing tables? d. A router using distance vector routing has the following routing table: Net2 6 A Net3 3 A Net4 4 E Net6 1 B Net7 2 D The router receives the following packet from router C: Net2 4 Net3 2 Net4 5 Net6 2 Net7 3 Show the updated routing table for the router. 6. a. If a bridge sends data from a Token Ring network to an Ethernet network how is a collision handled by the bridge? b. what is router s role in controlling the packet lifetime? 7. a. Find the subnetwork address for the following. Show the steps for your calculation. IP address: 200.34.22.156 Mask: 255.255.255.224 b. What is the maximum number of subnets in the following site? Show how you calculated the number. Site address: 217.14.8.0 Mask: 255.255.255.224 2
8. a. What you mean by encryption and decryption? Name some conventional methods of encryption and decryption with examples of their functions. Name two encryption/decryption standards. b. Define Authentication, digital signature. c. Explain RSA Encryption. What are the steps for calculating Kp, Ks, and N? Given the two prime numbers p=19 and q=23, find out N, Kp, and Ks. c. What is compression and why is necessary? Explain with examples lossy and lossless compression. 9. Given the following network. Boldface numbers indicate network addresses. host1 G1 G2 R1 network host2 R2 Answer the following questions: a. How many IP address the gateway G1, G2, and the router R1 should have? G1: G2: R1: b. Choose an appropriate address for network1? c. Choose the appropriate addresses for gateway G1 (based on your previous answers). d. Choose an appropriate addresses for host1 and host2. host1: host2: 10. a. What is the purpose of domain name system? b. What is the difference between boundary-level masking and nonboundary-level masking? 11. a. What are the 3 switching methods? b. How many cross points are needed in a single-stage switch with 41 inputs and 52 outputs? 12. a. Explain ARP and RARP protocols b. Explain BOOTP and DHCP protocols. Expalin what you mean by DNS. c. Explain the terms: Telnet, NVTFTP, SMTP, MTA, UA. 13. a. What is the LSP database, and how is it created? b. Given the following network. Find the shortest path tree and routing table for router B. Net Net Net Net: Net: Net: Net: 3
Multiple Choices Notes: Any script without a name will receive no points. NAME: (EXAM: SECTION B) Use Scantron to answer. It is necessary that you mark the correct answers on scantron page and also circle on this paper. 1. Which type of switching uses the entire capacity of a dedicated link? a. circuit switching b. datagram packet switching c. virtual circuit packet switching d. message switching 2. How many crosspoints are needed in a single-stage switch with 40 inputs and 50 outputs? a. 40 b. 50 c. 90 d.2000 3. A switched virtual circuit involves a. connection establishment b. data transfer c. connection release d. all of the above 4. To create a, combine crossbar switches in stages. a. multistage switch b. crosspoint c. packet switch d. TSI 5. A cell's header has a field. a. VPI b. VCI c. port d. a and b 6. The layer adds a 5-byte header to a 48-byte segment. a. AAL b. ATM c. physical d. SAR 7. The ATM layer accepts data in byte segments from the AAL layer. a. 44 b. 45 c. 47 d. 48 8. VPI is an acronym for. a. virtual path identifier b. virtual permanent identifier c. virtual packet identifier d. virtual port identifier 9. ATM is a cell relay protocol that. a. has moved software functions to hardware b. is connection-oriented c. can interface with existing systems d. all of the above 10. What is the main problem in multiplexing packets of different sizes? a. Smaller packets are always transmitted first. b. Larger packets are always transmitted first. c. Smaller packets may experience delayed transmission. d. Packets are transmitted according to size. 11. Which of the following is not an internetworking device? a. bridge b. gateway c. router d. all of them are 12. Which of the following uses the greatest number of layers in the OSI model? a. bridge b. repeater c. router d. gateway 13. A bridge forwards or filters a packet by comparing the information in its address table to the packet s a. layer 2 source address b. source node s physical address c. layer 2 destination address d. layer 3 destination address 14. A simple bridge does which of the following? a. filters a data packet b. forwards a data packet c. extends LANs d. all of the above 15. A simple bridge does which of the following? a. filters a data packet b. forwards a data packet c. extends LANs d. all of the above 4
16. The shortest path in routing can refer to a. the least expensive path b. the least distant path c. the path with the smallest number of hops d. any or a combination of the above 17. Which routing algorithm requires more traffic between routers for setup and updating? a. distance vector b. link state c. Dijkstra d. vector link 18. In distance vector routing, each router receives vectors from a. every router in the network b. every router less than two units away c. a table stored by the software d. its neighbors only 19. If there are five routers and six networks in an internetwork using link state routing, how many routing tables are there? a. 1 b. 5 c. 6 d. 11 20. The layer accepts transmissions from upper-layer services. a. AAL b. ATM c. physical d. SAR 21. In a virtual connection identifier, the VCI is bits in an UNI and bits in an NNI. a. 8; 16 b. 16; 8 c. 8; 8 d. 16; 16 22. The of a TSI controls the order of delivery of slot values that are store RAM. a. crossbar b. crosspoint c. control unit d.transceiver 23. If there are five routers and six networks in an internetwork, how many link state databases are there? a. 1 b. 5 c. 6 d. 11 24. Gateways function in which OSI layers? a. the lower three b. the upper four c. all seven d. all but the physical layer 25. Repeaters function in the layer(s). a. physical b. data link c. network d. a and b 26. Which type of bridge builds and updates its tables from address information on packets? a. simple b. transparent c. a and b d. none of the above 27. In, each packet of a message need not follow the same path from sender to receiver. a. circuit switching b. message switching c. the virtual approach to packet switching d. the datagram approach to packet switching 28. In, each packet of a message follows the same path from sender to receiver. a. circuit switching b. message switching c. the virtual approach to packet switching d. the datagram approach to packet switching 29. Routers function in the layers. a. physical and data link b. physical, data link, and network c. data link and network d. network and transport 30. In which routing method do all the routers have a common database? a. distance vector b. link state c. link vector d. none of the above 31. A packet traveling from one Token Ring network to another Token Ring network uses the services of a. (Each network is an independent network.) a. simple bridge b. repeater c. router d. transparent bridge 32. An IP address is bits. a. 24 b. 32 c. 48 d. none of the above 5
33. A class E address starts with the bit(s). a. 0 b. 10 c. 1110 d. 1111 34. In decimal notation, the first byte of a class E address should be between and. a. 0; 127 b. 192; 223 c. 224; 239 d. 240; 255 35. What is the class of the address 200.66.10.21? a. A b. B c. C d. E 36. What is the netid of the address 200.66.10.21? a. 200 b. 200.66 c. 200.66.10 d. none of the above 37. What is the hostid of the address 12.11.1.21? a. 11.1.21 b. 1.21 c. 21 d. none of the above 38. In link state routing, flooding allows changes to be recorded by a. all routers b. neighbor routers only c. some routers d. all networks 39. In an LSP, the advertiser is a. a router b. a network c. a data packet d.none of the above 40. Which of the following can be handled by a gateway? a. protocol conversion b. packet resizing c. data encapsulation d. a and b 41. What is the hostid of the address 200.66.10.21? a. 66.10.21 b. 10.21 c. 21 d. none of the above 42. What is the address of the network to which the host 130.8.119.1 is connected (no subnetting)? a. 130.8.119.0 b. 130.8.0.0 c. 130.0.0.0 d. none of the above 43. Using a host address 195.21.43.65 and the mask 255.255.255.192, the subnetwork address is. a. 195.21.43.0 b. 195.21.0.0. c. 195.21.43.64 d. none of the above 44. IP addresses without subnetting have level(s) of hierarchy. a. 3 b. 2 c. 1 d. none of the above 45. In a cell network, cells belonging to a single message. a. may follow different paths b. may arrive out of order c. require extensive additional addressing and control information d. follow the same path 46. The VPI identifies a. a. cell b. station c. virtual path d. virtual packet 47. An ATM cell consists of bytes. a. 48 b. 53 c. 256 d. a variable number of 48. A class C address starts with the bit(s). a. 0 b. 10 c. 110 d. 1110 49. In decimal notation, the first byte of a class D address should be between and. a. 0; 127 b. 128; 191 c. 224; 239 d. 240; 255 50. Which of the following are bridge types? a. simple, complex, transparent b. simple, transparent, multiport c. simple, complex, multiport d. spanning, contract, suspension 51. The shortest path in routing can refer to a. the least expensive path b. the least distant path c. the path with the smallest number of hops d. any or a combination of the above 6
52. Which routing algorithm requires more traffic between routers for setup and updating? a. distance vector b. link state c. Dijkstra d. vector link 53. In distance vector routing, each router receives vectors from a. every router in the network b. every router less than two units away c. a table stored by the software d. its neighbors only 54. If there are five routers and six networks in an internetwork using link state routing. how many routing tables are there? a. 1 b. 5 c. 6 d. 11 55. If there are five routers and six networks in an internetwork, how many link state databases are there? a. 1 b. 5 c. 6 d. 11 56. Bridges function in the layer(s). a. physical b. data link c. network d. a and b 57. What type of bridge must have its address table entered manually? a. simple b. transparent c. multiport d. b and c 58. In link state routing, flooding allows changes to be recorded by a. all routers b. neighbor routers only c. some routers d. all networks 59. In an LSP, the advertiser is a. a router b. a network c. a data packet d. none of the above 60. Which of the following can be handled by a gateway? a. protocol conversion b. packet resizing c. data encapsulation d. a and b 61. Gateways function in which OS! layers? a. the lower three b. the upper four c. all seven d. all but the physical layer 62. Which of the following best describes a cell network? a. All packets carry audio or video data. b. All packets are the same size. c. The packet size is variable, but less than 4096 bytes. d. all of the above 63. The is a device that connects n inputs to m outputs. a. crosspoint b. crossbar c. modem d. RAM 64.In which type of switching do all the datagrams of a message follow the same channels of a path? a. circuit switching b. datagram packet switching c. virtual circuit packet switching d. message switching 65. In a crossbar with 1000 crosspoints, how many statistically are in use at any time? a. 100 b. 250 c. 500 d. 1000 66. The of a TSI controls the order of delivery of slot values that are store RAM. a. crossbar b. crosspoint c. control unit d. transceiver 67. In circuit switching, delivery of data is delayed because data must stored and retrieved from RAM. a. space-division b. time-division c. virtual d. packet 68. A switched virtual circuit involves a. connection establishment b. data transfer c. connection release d. all of the above 69. A permanent virtual circuit involves a. connection establishment b. data transfer c. connection release d. all of the above 70. To create a, combine crossbar switches in stages. 7
a. multistage switch b. crosspoint c. packet switch d. TSI 71. Which of the following is a time-division switch? a. TSI b. TDM bus c. crosspoint d. a and b 72. In a time-division switch, a governs the destination of a packet stored in RAM. a. TDM bus b. crosspoint c. crossbar d. control unit 73. The PSTN is an example of a network. a. packet-switched b. circuit-switched c. message-switched d. none of the above 74. ATM can use as a transmission medium. a. twisted-pair cable b. coaxial cable c. fiber-optic cable d. all of the above 75. In data communications, ATM is an acronym for a. Automated Teller Machine b. Automatic Transmission Model c. Asynchronous Telecommunication Method d. Asynchronous Transfer Mode 76. Because ATM, which means that cells follow the same path, the cells do not usually arrive out of order. a. is asynchronous b. is multiplexed c. is a network d. uses virtual circuit routing 77. Which layer in ATM protocol reformats the data received from other networks? a. physical b. ATM c. application adaptation d. data adaptation 78. Which layer in ATM protocol has a 53-byte cell as an end product? a. physical b. ATM c. application adaptation d. cell transformation 79. A field on a UNI cell header is used for connection purposes. a. VPI (virtual path identifier) b. VCI (virtual circuit identifier) c. CLP (cell loss priority) d. GFC (generic flow constant) 80. A field on a cell header in the ATM layer determines whether a cell can be dropped. a. VPI (virtual path identifier) b. VCI (virtual circuit identifier) c. CLP (cell loss priority) d. GFC (generic flow constant) 81. ATM multiplexes cells using a. asynchronous FDM b. synchronous FDM c. asynchronous TDM d. synchronous TDM 82. In an ATM network, all cells belonging to a single message follow the same and remain in their original order until they reach their destination. a. transmission path b. virtual path c. virtual circuit d. none of the above 83. A provides a connection or a set of connections between switches. a. transmission path b. virtual path c. virtual circuit d. none of the above 84. A is the physical connection between an end point and a switch or between two switches. a. transmission path b. virtual path c. virtual circuit d. none of the above 85. The VPI of a UNI is bits in length. a. 8 b. 12 c. 16 d. 24 86. The VPI of an NNI is bits in length. a. 8 b. 12 c. 16 d. 24 87. In a VP switch the does not change while the can change. a. VPI, VCI b. VCI;VPI c. VP;VPC d. VPC;VP 88. In a switch, both the VPI and the VCI can change. a. VP b. VPC c. VPI d. VCI 8
89. The cell is the difference between the CTD maximum and minimum. a. loss ratio b. transfer delay c. delay variation d. error ratio 90. The cell is the ratio of lost cells to cells sent. a. loss ratio b. transfer delay c. delay variation d. error ratio 91. The service class is particularly suitable for applications with bursty data. a. CBR b. VBR c. ABR d. UBR 92. The service class is suitable for customers who need real-time video transmission. a. CBR b. VBR c. ABR d. UBR 93. The is greater than the SCR. a. PCR b. MCR c. CVDT d. all of the above 94. measures the variation in cell transmission time. a. SCR b. PCR c. MCR d. CVDT 95. If the SCR is 60,000, the PCR is 70,000, and the MCR is 55,000, what is the minimum number of cells that can be sent per second? a. 55,000 b. 60,000 c. 70,000 d. 5000 96. The is the fraction of the cells delivered in error. a. CLR b. CTD c. CDV d. CER 97. If the maximum CTD is 10 microseconds and the minimum CTD is 1 microsecond, the is 9 microseconds. a. CLR b. CTD c. CDV d. CER 98. is software that allows an ATM switch to emulate a LAN switch. a. LEC b. BUS c. BES d. LANE 99. The server software allows multicasting and broadcasting on an ATM LAN. a. LEC b. BUS c. BVD d. BES 100. Repeaters function in the layer(s). a. physical b. data link c. network d. a and b 101. Bridges function in the layer(s). a. physical b. data link c. network d. a and b 102. A repeater takes a weakened or corrupted signal and it. a. amplifies b. regenerates c. resamples d. reroutes 103. A bridge has access to the address of a station on the same network. a. physical b. network c. service access point d. all of the above 104. What type of bridge must have its address table entered manually? a. simple b. transparent c. multiport d. bandc 105. Which type of bridge builds and updates its tables from address information on packets? a. simple b. transparent c. a and b d. none of the above 106. Routers function in the layers. a. physical and data link b. physical, data link, and network c. data link and network d. network and transport 107. In which routing method do all the routers have a common database? a. distance vector b. link state c. link vector d. none of the above 9
108. A packet traveling from one Token Ring network to another Token Ring network uses the services of a. (Each network is an independent network.) a. simple bridge b. repeater c. router d. transparent bridge 110. In the conventional method of encryption and decryption, which key is publicly known? a. Ke only b. Kd only c. Ke and Kd d. none 111. In the public key method of encryption and decryption, which key is publicly known? a. Ke only b. Kd only c. Ke and Kd d. none 112. In the public key method of encryption and decryption, only the receiver has possession of the a.ke b.kd c. Ke and Kd d. none of the above 113. We use an encryption method in which both plaintext and ciphertext have the same number of As, Bs, Cs, and so on. This is probably substitution. a. monoalphabetic b. polyalphabetic C. transpositional d. rotational 114. We use an encryption method in which the character Z always substitutes for the character G. This is probably substitution. a. monoalphabetic b. polyalphabetic c. transpositional d. rotational 115. We use an encryption method in which the plaintext AAAAAA becomes the ciphertext BCDEFG. This is probably substitution. a. monoalphabetic b. polyalphabetic c. transpositional d. DES 116. An encryption method used by the U.S. government for nonmilitary and nonclassifled use is a. monoalphabetic substitution b. polyalphabetic substitution c. transpositional substitution d. the data encryption standard 117. In permutation, the number of outputs is greater than the number of inputs. a. a straight b. a compressed c. an expanded d. a rotational 118. The RSA algorithm is the basis of a encryption method. a. public key b. private key c. conventional d. denominational 119. The success of the RSA encryption method lies in the difficulty of a. finding Kp b. finding the prime factors of Kp c. finding N d. finding the prime factors of N 120. Data are compressed using pointers to frequently used strings. This is a. differential encoding b. Lempel-Ziv-Welch encoding c. Morse coding d. lossy coding 121. Data are compressed by sending just the differences between video frames. This is a. differential encoding b. Lempel-Ziv-Welch encoding C. Morse coding d. lossy coding 122. A string of 100 Os is replaced by a marker, a 0, and the number 100. This is a. run-length encoding b. Morse code c. differential encoding d. Lempel-Ziv-Welch encoding 123. An example of lossy compression is a. differential encoding b. Lempel-Ziv-Welch encoding c. run-length encoding d. JPEG 10