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B227 Data Communications Quiz 1 2001 Directions You are required to place you answers on a computer readable answer sheet. Hand your completed sheet in at the end of the quiz. Remember! Place your name and student No. on the answer sheet. KEEP YOUR EYES ON YOUR OWN PAPER!!! 1. a) b) c) d) are rules that govern a communication exchange. Media Criteria Protocols all of the above 2. Frequency of failure and network recovery time after a failure are measures of the a network. a) performance b) reliability c) security d) feasibility of 3. The performance of a data communications network depends on a) the number of users b) the transmission media c) the hardware and software d) all of the above 4. Viruses are a network a) performance b) reliability c) security d) all of the above issue. 5. Which organization consists of computer scientists and engineers and is known for its development of LAN standards? a) EIA b) ITU-T c) ANSI d) IEEE 6. is the division of one task among multiple computers. e) Distributed processing f) Distributed massaging g) Distributed telephony h) Electronic massaging Page 1 B227 Data Communications Quiz 1 2001 7. If a protocol specifies that data should be sent at 100 Mbps, this is a a) syntax b) semantics c) timing d) none of the above issue. 8. When a protocol specifies that the address of the sender must occupy the first four bytes of a message, this is a issue. e) syntax f) semantics g) timing h) none of the above 9. When a protocol specifies that the address of the sender means the most recent sender and not the original source, this is a issue. a) syntax b) semantics c) timing d) none of the above 10. What is the main difference between a de facto standard and a de jure standard? a) A de facto standard has been legislated by an officially recognized body; a de jure standard has not. b) A de jure standard has been legislated by an officially recognized body; a de facto standard has not. c) The inventing company can wholly own a de jure standard and not a de facto standard. d) A de jure standard is proprietary; a de facto standard is not. 11. Which topology requires a central controller or hub? a) mesh b) star c) bus d) ring 12. Communication between a computer and a keyboard involves a) simplex b) half-duplex c) full-duplex d) automatic 13. A a) b) c) d) transmission. connection provides a dedicated link between two devices. point-to-point multipoint primary secondary Page 2 B227 Data Communications 14. In Quiz 1 2001 transmission, the channel capacity is shared by both communicating devices at all times. a) Simplex b) half-duplex c) full-duplex d) half-simplex 15. MacKenzie Publishing, with headquarters in London and branch offices throughout Asia, Europe, and South America, is probably connected by a . a) LAN b) MAN c) WAN d) none of the above 16. BAF Plumbing has a network consisting of two workstations and one printer. This is most probably a . a) LAN b) MAN c) WAN d) none of the above 17. A cable break in a a) mesh b) bus c) star d) primary topology stops all transmission. 18..A network that contains multiple hubs is most likely configured in a a) mesh b) tree c) bus d) star 19. The OSI model consists of a) three b) five c) seven d) eight 20. The a) b) c) d) layers. layer decides the location of synchronization points. transport session presentation application Page 3 topology. B227 Data Communications Quiz 1 2001 21. The end-to-end delivery of the entire message is the responsibility of the a) network b) transport c) session d) presentation 22. The a) b) c) d) layer is the layer closest to the transmission medium. physical data link network transport 23. In the a) b) c) d) physical data link network transport layer. layer, the data unit is called a frame. 24. Decryption and encryption of data are the responsibility of the a) physical b) data link c) presentation d) session layer. 25. As the data packet moves from the upper to the lower layers, headers are a) added b) removed c) rearranged d) modified . 26. When data are transmitted from device A to device B, the header from A’s layer 5 is read by B's layer. a) physical b) transport c) session d) presentation 27. The a) b) c) d) layer changes bits into electromagnetic signals. physical data link transport presentation Page 4 B227 Data Communications 28. The a) b) c) d) Quiz 1 2001 layer can use the trailer of the frame for error detection. physical data link transport presentation 29. The physical layer is concerned with the transmission of medium. a) programs b) dialogs c) protocols d) bits over the physical 30. Which of the following is an application layer service? a) network virtual terminal b) file transfer, access, and management c) mail service d) all of the above 31. In a time-domain plot, the vertical axis is a measure of. a) amplitude b) frequency c) phase d) time 32. As frequency increases, the period a) decreases b) increases c) remains the same d) doubles . . 33. A sine wave is . a) periodic and continuous b) aperiodic and continuous c) periodic and discrete d) aperiodic and discrete 34. If the baud rate for a QAM signal is 1800 and the bit rate is 9000, how many bits are there per signal element? a) 3 b) 4 c) 5 d) 6 Page 5 B227 Data Communications Quiz 1 2001 35. Which conversion type needs sampling of a signal? a) digital-to-digital conversion b) analog-to-digital conversion c) digital-to-analog conversion d) all of the above 36. Modulation of an analog signal can be accomplished through modulation of the the carrier signal. a) amplitude b) frequency c) phase d) any of the above 37. Transmission media are usually categorized as e) fixed or unfixed f) guided or unguided g) determinate or indeterminate h) metallic or non-metallic 38. a) b) c) d) . cable consists of an inner copper core and a second conducting outer sheath. Twisted-pair Coaxial Fiber-optic Shielded twisted-pair 39. At the lower end of the electromagnetic spectrum we have a) radio waves b) power and voice c) ultraviolet light d) infrared light 40. of . are the highest frequency electromagnetic waves in use for data communications. a) Visible light waves b) Cosmic rays c) Radio waves d) Gamma rays 41. Smoke signals are an example of communication through a) a guided medium b) an unguided medium c) a refractive medium d) a small or large medium Page 6 . B227 Data Communications Quiz 1 2001 42. In an optical fiber, the inner core is a) more dense than b) less dense'than c) the same density as d) another name for 43. In a) b) c) d) . propagation, low-frequency radio waves hug the earth. surface tropospheric ionospheric space 44. If a satellite is in geosynchronous orbit, it completes one orbit in a) one hour b) 24 hours c) one month d) one year . 45. is a type of transmission impairment in which the signal loses strength due to the resistance of the transmission medium. a) Attenuation b) Distortion c) Noise d) Decibel 46. is a type of transmission impairment in which the signal loses strength due to the different propagation speed of each frequency that makes up the signal. a) Attenuation b) Distortion c) Noise d) Decibel 47. is a type of transmission impairment in which an outside source such as crosstalk corrupts a signal. a) Attenuation b) Distortion c) Noise d) Decibel 48. The performance of transmission media can be measured by a) throughput b) propagation speed c) propagation time d) all of the above Page 7 . B227 Data Communications Quiz 1 2001 49. Error detection is usually done in the a) physical b) data link c) network d) any of the above layer of the OSI model. 50. Which error detection method involves polynomials? a) VRC b) LRC c) CRC d) checksum 51. Which of the following best describes a single bit error? a) A single bit is inverted. b) A single bit is inverted per data unit. c) A single bit is inverted per transmission. d) any of the above 52. Which OSI layer corresponds to the TCP-UDP layer? a) Physical b) Data link c) Network d) Transport 53. Which OSI layer corresponds to the IP layer? a) Physical b) Data link c) Network d) Transport 54. Which OSI layer(s) correspond to TCP/IP’s application layer? a) Application b) Presentation c) Session d) All of the above 55. The data unit in the TCP/IP data link layer is called a a) Message b) Segment c) Datagram d) Frame End of Quiz Page 8 .