Data Communications

1. The process of transferring digital information between two or more points.a. Data communicationsb. Wireless communicationsc. Wire communicationsd. None of the aboveAnswer: A

2. Information that has been processed and organized.a. Knowledgeb. Data c. Telegraph d. Telephone Answer: B

3. Invented the telegraph.a. Emile Baudotb. Samuel F.B. Morsec. Alexander Graham Belld. Thomas EdisonAnswer: B

4. A device which allowed signals from up to six different telegraph equipments.a. Telephone setb. Equipment converterc. Telegraph multiplexerd. Add/Drop MultiplexerAnswer: C

5. The international organization for standardization. It creates the sets of rules and standards for graphics, document exchange, and related technologies. Responsible for endorsing and coordinating the work of the other standards organizations.a. ANSIb. ISOc. OSId. IEEEAnswer: B

6. What is the transmission mode between the DCE and DTE?a. Parallel transmissionb. Serial transmissionc. Both serial and paralleld. None of the aboveAnswer: B

7. A general term that describes the interface equipment used at the stations to adapt the digital signals from the computers and terminals to a form more suitable for transmission.a. DTEb. DCEc. Modem d. Transmission mediumAnswer: A

8. It is called parallel-by-bit or serial-by-character transmission.a. Parallel data transmission.b. Serial data transmission.c. Both serial and parallel.d. None of the above..Answer: A

9. There is a single transmission line used. Only one bit is transmitted at a time. It is often called serial-by-bit transmission. Used for long distance communications.a. Parallel data transmission.b. Serial data transmission.c. Both serial and parallel.d. None of the above.Answer: B

10. This exchange of signals such as DA (Data is Available) and DU(Data is Unavailable) between the sender and the receiver is called aa. Poll.b. Handshakec. Control.d. None of the above.Answer: B

11. A general term that describes the equipment that converts digital signals to analog signals and interfaces the DTE to the analog transmission mediuma. DTEb. DCEc. Modem d. Transmission mediumAnswer: B

12. Which is faster data transmission?a. Parallel transmission.

b. Serial transmission.c. The same.d. None of the above.Answer: A

13. The transmission in only one direction is calleda. Simplex b. Half-duplex.c. Full-duplex.d. Full/Full-duplex.Answer: A

14. The transmit and receive signals must be in different frequency band.a. Two-wire operation.b. Four-wire operation.c. Hybrid connection.d. None of the above.Answer: A

15. This refers to the way in which data is represented.a. Character set.b. Character code.c. Data Communication code.d. All of the above.Answer: D

16. Used to facilitate the orderly flow of data from a source to destination.a. Data-link control character.b. Graphic control character.c. Alphanumeric character.d. All of the above.Answer: A

17. The first data communication code.a. Morse code.b. Baudot code.c. ASCII.d. EBCDIC.Answer: A

18. Recommended by CCITT as International Alphabet No. 2.a. Morse code.b. Baudot code.c. ASCII.d. EBCDIC.Answer: B

19. Also known as Telex code.a. Morse code.b. Baudot code.c. ASCII.d. EBCDIC.

Answer: B20. Recommended by CCITT as

International Alphabet No. 5.a. ASCII.b. EBCDIC.c. Baudot Code.d. Morse Code.Answer: A

21. An 8-bit character code developed by IBM and used extensively on IBM compatible equipments.a. ASCII.b. EBCDIC.c. Baudot Code.d. Morse Code.Answer: B

22. The process of monitoring the received data and determining when a transmission error occurred.a. Error control.b. Error detection.c. Error correction.d. None of the above.Answer: B

23. The transmission of each character or each message multiple times until it is properly received.a. CRC.b. LRC.c. VRC.d. Redundancy.Answer: D

24. An error detection where there is the same number of 1’s in each character.a. Redundancy.b. Exact-count encoding.c. VRC.d. FEC.Answer: B

25. A bit added to a data to force the number of 1 to be odd or even.a. Hamming bit.b. BCC.c. Parity.d. CRC.Answer: C

26. Involves the process of error correction and detection.a. Error control.b. Data link control.

c. Network control.d. Session control.Answer: A

27. A code developed by Thomas Murray.a. Baudot codeb. Murray codec. Da Vinci coded. None of the aboveAnswer: A

28. International Standard V.41 recommends the use ofa. VRC.b. LRCc. CRC-16.d. CRC-41.Answer: C

29. Designed to be used in a human environment where a human is present to analyze the received data and make decisions on its integrity.a. Retransmission.b. Symbol substitution.c. Forward error correction.d. All of the above.Answer: B

30. Detects and corrects transmission errors at the receive end without calling for retransmission.a. Retransmission.b. Symbol substitution.c. Forward error correction.d. All of the above.Answer: C

31. The most reliable error detection scheme which detects almost 99.95% of all transmission errors.a. CRC.b. VRC.c. ARQ.d. VRC.Answer: A

32. The code used in forward error correction.a. ASCII.b. Baudot.c. Hamming code.d. EBCDIC.Answer: C

33. Each character is framed between a start and a stop bit.

a. Asynchronous data format.b. Synchronous data format.c. Both synchronous and asynchronous.d. None of the above.Answer: A

34. The SYN character in ASCII.a. 16H.b. 32H.c. 64H.d. 08H.Answer: A

35. At the primary station serves as an interface between the host computer and the circuits that it serves.?a. Line control unit.b. USRT.c. UART.d. USART.Answer: A

36. Interface coordinates the flow of data, control signals and timing information between the DTE and the DCE.a. Parallel interface.b. Serial interface.c. Both parallel and serial interface.d. None of the above.Answer: B

37. The number of Hamming bits that must be added to a character is determined bya. 2n ≥ m + n + 1b. 2n ≤ m + n + 1c. 2n = m + n + 1d. 2n ≠ m + n + 1Answer: A

38. The terminal load capacitance of the RS-232C cable is specified as ____ which includes cable capacitance.a. 2500 pF.b. 2500 nF.c. 250 pF.d. 250 nF.Answer: A

39. The output impedance of RS-232C must be greater than ____ ohmsa. 200b. 300c. 400d. 1000

Answer: B40. Maximum bit rate of RS-232C.

a. 20 kbpsb. 30 kbpsc. 56 kbpsd. 128 kbpsAnswer: B

41. Connecting a DTE to another DTE requiresa. Serial interface.b. Parallel interface.c. A null modem.d. All of the above.Answer: C

42. Updated version of RS-232C serial interface.a. RS-232D.b. RS-449A.c. X.21 interface.d. None of the aboveAnswer: B

43. Minimum data rate of X.21 interface.a. 56 kbps.b. 20 kbps.c. 64 kbps.d. 48 kbps.Answer: C

44. This interfaces between the CSU and the customers equipment, using RS232 for low speeds up to 56Kbps, and V.35 (RS-422/499) for higher speeds.a. Modem.b. X.21 interfacec. Leased lined. Data Service Unit.Answer: D

45. T1 data rate isa. 1.544 Mbps.b. 2.048 Mbps.c. 512 kbps.d. None of the above.Answer: A

46. Modem with speed of less than or equal to 2000 bps.a. Low-speed modem.b. Medium-speed modem.c. High-speed modem.d. Smart modem.Answer: A

47. A set of rules which governs how data is sent from one point to another.a. Constitution.b. Code.c. Recommendation.d. Protocol.Answer: D

48. A set of standards for communications among computers; its primary purpose is to serve as a structural guideline for exchanging information between computers, terminals, and networks.a. Cisco.b. TCP/IP.c. OSI.d. All of the above.Answer: C

49. A device which operates on all seven OSI layers.a. Repeater.b. Bridge.c. Router.d. Gateway.Answer: D

50. A network device used in the data-link layer.a. Repeater b. Bridge c. Router d. GatewayAnswer: B

51. A device operating in the network layer isa. Repeaterb. Bridge.c. Router.d. Gateway.Answer: C

52. An OSI layer that determines which network configuration (dial up, leased, or packet) is most appropriate for the function provided by the network.a. Physical layer.b. Data-link layer.c. Network later.d. Presentation layer.

Answer: C53. Standards outlined in the physical layer.

a. Functional b. Procedural c. Electrical d. All of the above.Answer: D

54. An OSI layer which is responsible for communicating between primary and secondary nodes within the network.a. Physical layer.b. Network layer.c. Session layerd. Data-link layer.Answer: D

55. It defines the mechanism in which messages are broken into data packets and routed from a sending node to a receiving node within a communication network.a. Presentation layer.b. Application layer.c. Network layer.d. Data-link layer.Answer: C

56. What are the two sub-layers of the data-link?a. Logical Link Control and Media

Access Control.b. Media Access Control and Internet

Protocol Control.c. Logical Link Control and Internet

Protocol Controld. None of the aboveAnswer: A

57. Controls the end-to-end integrity of the message, which includes message routing, segmenting and error recovery.a. Physical layer.b. Network layer.c. Session layer.d. Presentation layer.Answer: D

58. It is the highest layer in terms of communications.a. Physical layer.b. Network layer.

c. Session layer.d. Presentation layer.Answer: D

59. Addresses any code or syntax conversion necessary to present the data to the network in a common format for communications.a. Session layer.b. Presentation layer.c. Application layer.d. Network layerAnswer: B

60. It performs code and character set translation and determines the display mechanism for messages.a. Session layer.b. Presentation layer.c. Application layer.d. Network layerAnswer: B

61. Responsible for network availability (i.e., buffer storage and processor capacity).a. Physical layer.b. Network layer.c. Session layer.d. Presentation layer..Answer: C

62. It is a character-oriented protocol. It uses VRC as the only type of error detection. Symbol substitution and ARQ (retransmission) are used for error correction. The polling sequence usually encompasses sending one or two data link control characters, then a station polling address.a. Asynchronous protocolsb. Synchronous protocols.c. Bisync protocol.d. None of the above.Answer: A

63. It controls the sequence of activities within an application and also the sequence of events between the computer application and the user of another application. It communicates

directly with the user’s application program.a. Network layer.b. Presentation layer.c. Session layer.d. Application layer.Answer: D

64. The flag used with HDLC.a. 7EH.b. FFH.c. AAH.d. 55H.Answer: A

65. Its responsibilities include network log-on and log-off procedures and user authentication. It determines the type of dialogue available (i.e., simplex, half-duplex or full-duplex).a. Session layer.b. Presentation layer.c. Application layer.d. Network layer.Answer: A

66. Bisync is an example ofa. Asynchronous protocol.b. Synchronous protocol.c. Character-oriented protocol.d. Sliding window protocol.Answer: B

67. For a terminal operator to enter information into his computer terminal, the terminal must be in thea. Transmit.b. Line monitoring mode.c. Local mode.d. Receive mode.Answer: C

68. A group of devices is calleda. Cellsb. Cluster.c. Poll.d. None of the above.Answer: B

69. A negative acknowledgement in response to a poll.a. /C.b. Handshake.c. SYN d. PADAnswer: B

70. Which of the following is used as a Packet Assembler and Disassembler sequence?a. AAHb. 55Hc. AAH or 55H.d. None of the aboveAnswer: C

71. The character language used in SDLC isa. ASCII.b. EBCDIC.c. CRC.d. Baudot.Answer: B

72. A broadcast address used in asynchronous protocols.a. 7EH.b. AAH.c. FFHd. 55H.Answer: C

73. The null address which is used in testing LAN isa. 00H.b. FFH.c. AAH.d. 55H.Answer: A

74. An idle stage is presumed with an SDLC after how many seconds of continuous reception of 1’s?a. 10 seconds.b. 15 seconds.c. 20 seconds.d. 30 seconds.Answer: B

75. A SDLC frame which can be used for transmission of data or control commands.a. Information frame.b. Supervisory frame.c. Unnumbered frame.d. None of the above.Answer: C

76. Operational mode of HDLC in which secondary stations are allowed to send unsolicited responses; to transmit, a secondary does not need to have received a frame from the primary with the P bit set.

a. ADMb. ARM.c. DIM.d. RIM.Answer: B

77. Identical to the normal disconnect mode except that the secondary can initiate a Disconnect Mode (DM) or Request Initialization Mode (RIM) response anytime.a. ADM.b. ARM.c. SIM.d. None of the above.Answer: A

78. .