Digital Design Interview QuestionsFull description
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MITRC REFRESHER COURSE Telephony
ANSWER KEY
Datacom & Digital
1.
Redundancy means the ________ a. Transmission rate of the system b. Symbols are to be repeated c. Time between failures d. Time between successes
2.
The digital information is contained in both the amplitude and phase of the modulated carrier. a. PSK b. FSK c. QAM d. ASK
3.
The input signal is a binary digital signal and a limited number of out put phases are possible. a. PSK b. FSK c. QAM d. ASK
4.
A radio channel is composed of ___VB channels. a. 1800 b. 900 c. 10800 d. 8064
12. Use of coaxial cables in interconnecting networks is limited to an overall length of __. a. 1500 ft b. 1500 m c. 1500 km d. 1500 kft
5.
What equation defines the composition of an ISDN basic access line? a. 2B + D b. B + D c. B + 2D d. 2B + 2D
13. What identifies how the stations are interconnected in a network? a. Topology b. Architecture c. Topology or architecture d. Topology and architecture
6.
A digital network where voice, video, text and data are multiplied into a single network for processing and are transmitted prior to use. a. Frame delay b. Asynchronous transfer mode (ATM) c. ISDN d. Synchronous digital hierarchy(SDH)
14. _______is a data communications network designed to provide two-way communications between a large varieties of data communication terminal equipment within a relatively small geographic area a. Private Area network b. Local Area Network c. Wide area network d. Ethernet
7.
Non-ISDN equivalent can be connected to ISDN line by the use of ____. a. Terminal equipment b. Terminal adapter c. Modem d. Network adaptor
8.
9.
a. b. c. d.
2n = m+ n +1 2n > m +n +1 2n > m +n +1 2n < m +n +1
10. What determine which network configuration is most appropriate? a. Application layer b. Presentation layer c. Network layer d. Data link layer 11. Ethernet is a baseband system using CSMA/CD operating at ____ a. 10 Mbps b. 20 Mbps c. 30 Mbps d. 40 Mbps
15. ______ is the mode of transmission in public data network in which data are transferred from source to the network then to the destination in an asynchronous data format a. Synchronous mode b. Start/stop mode c. Packet mode d. Circuit mode
A special voice encoder/decoder used in digitizing speech signal only is a. PCM b. PWM c. Vocoder d. PFM
16. A seven digit character can represent one of______ possibilities. a. 7 b. 14 c. 64 d. 128
Equation used to determine the number of Hamming bits in the hamming code. 1
MITRC REFRESHER COURSE Telephony
Datacom & Digital
17. ______ is defined to be the maximum rate at which information can be transmitted through a channel. a. Bit rate b. Baud rate c. Coding d. Channel capacity
b. c. d.
Expanding Encoding Companding
26. _______uses a single bit PCM code to achieve a digital transmission of analog signal a. Quadrature Amplitude Modulation b. Frequency Shift Keying(FSK) c. Delta Modulation(DM) d. Phase Modulation(PM)
18. Who developed the fixed-length binary code for telegraphy? a. Samuel Morse b. Emile Baudot c. Alexander Graham Bell d. Guglielmo Marconi
27. The line speed of bell system T1 carrier system is a. 64 kbps b. 3.152 Mbps c. 1.544 Mbps d. 6.312 Mbps
19. Inventor of pulse-code modulation for the digital encoding of speech signals. a. R.V.L. Hartley b. J.R. carson c. H. Nyquist d. Alex Reeves
28. How many channels does a super group have? a. 60 b. 600 c. 1800 d. 10800
20. Serial binary data interchange between DTE and DCE at rates up to 20 kbps. RS 232 is its EIA equivalent. a. V.26 b. V.24 c. V.42 d. V.32
29. The output frequency at the channel combiner of channel 7 is a. 76 – 80 kHz b. 80 – 84 kHz c. 84 – 88 kHz d. 88 – 92 kHz
21. RS 232 is normally an interface between DTE and DCE. What is its signal rate? a. 20 kbps b. 30 kbps c. 40 kbps d. 50 kbps
30. ________was the first fixed length 5-bit character code. a. EBCDIC b. ASCII c. Morse code d. Baudot code
22. What is multiplexing? a. The process of increasing bandwidth on a channel b. A technique that enables more than one data source to share the use of a common line c. Mailing letter at the post office d. The ability to share frequency by time
31. Amplitude shift keying is also known as ______. a. Up/down keying b. On/off keying c. Front/back keying d. I/O keying 32. PCM system require_________. a. Analog signal b. Large bandwidth c. Digital signals d. Fiber optics cable
23. In ____ modulation the carrier is a periodic train pulses. a. Amplitude b. Analog c. Digital d. Pulse
33. Which theorem sets the limit on the maximum capacity of a channel with a given noise level? a. Nyquist theorem b. Hartley theorem c. Shannon-Hartley theorem d. Shannon theorem
24. Which of the following pulse modulation techniques is a digital transmission system? a. Pulse duration modulation b. Pulse position modulation c. Pulse width modulation d. Pulse code modulation
34. _______is the difference between the original and reconstructed signal. a. Quantizing noise b. Fade margin
25. A process where the higher amplitude analog signals are compressed prior to transmission then expanded at the receiver. a. Compressing 2
MITRC REFRESHER COURSE Telephony c. d.
ANSWER KEY
Noise margin Noise figure
Datacom & Digital
43. A _____ that interconnects LAN having identical protocols at the physical and data link layers. a. Bridge b. Router c. Gateway d. Hub
35. What are the steps to follow to produce a PCM signal? a. Sampling,coding and quantizing b. Sampling,quantizing and coding c. Quantizing,sampling and coding d. Coding, quantizing and sampling
44. A _____ that interconnects LAN that has totally different protocols and format a. Bridge b. Router c. Gateway d. Hub
36. ________ identifies how the different stations in a multipoint system are interconnected. a. Network topology b. Star network c. Ring topology d. Bus network
45. All bits in a character can be sent/received simultaneously. a. Serial data b. Parallel data c. Full duplex d. Half duplex
37. A transmission where data are inputted directly on the cable. a. Broadband b. Base band c. Digital d. Analog
46. A system that perform parallel-to-series conversion of a data link. a. DTE b. DCE c. Modem d. FEP
38. Synchronous modems cost more than asynchronous modems because a. They are larger b. They must contain clock recovery circuits c. The production volume is larger d. They must operate on a larger bandwidth
47. Which mode of transmission achieves less than full-duplex but more than half-duplex. a. Full/full duplex b. Echoplex c. Isochronous d. synchronous
39. When one station is designated as master and the rest of the stations are considered slaves, message handling is _______. a. store and forward b. polling c. CSMA/CD d. Token passing
48. Rules governing the transmission of digital information. a. Data communications standard b. Line protocol c. Isochronous d. Digital communications
40. A store and forward switching. a. Circuit switching b. Packet switching c. Message switching d. PSTN
49. Codes must be a. Eight bits per character b. Either seven or eight bits per character c. Agreed upon in advance between sender and receiver d. The same in all modem computers
41. A timing signal generated by an oscillating circuit that is used to synchronize data transmission. a. Clock b. Start bit c. Quantizing d. BCC
50. Clear to send is a signal passed from the local modem to the local terminal when data port is ready to transmit data. It usually occurs in response to a. Data set ready b. Request to send c. Data terminal ready d. Data carrier detect
42. Which system allows different types of networks to be linked together? a. OSI b. CCITT c. Bell System d. AT & T
51. Digital to analog converter in synchronous modems send signals to the a. Modulator 3
MITRC REFRESHER COURSE Telephony b. c. d.
Datacom & Digital
Transmission lines Terminal equalizer
60. A quadratic signaling has _____ possible states. a. 16 b. 4 c. 8 d. 32
52. What is the data rate of the ISDN Basic access B channel? a. 32 kbps b. 64 kbps c. 144 kbps d. 192 kbps
61. What is the smallest unit of information in binary transmission system? a. Byte b. Digit c. Bit d. Nibble
53. How many bits are there to present 8 combinations? a. 3 b. 4 c. 2 d. 5
62. The lowest layer in the ISO protocol hierarchy. a. network layer b. physical layer c. transport laye d. datalink layer
54. How many number of equiprobable events are there for 8-bits of information? a. 256 b. 132 c. 2400 d. 512
63. Modem is referred to as a. Universal asynchronous receiver transmitter b. Universal synchronous receiver transmitter c. Data terminal equipment d. Data communication equipment
55. Which character code is used without parity bit? a. CCITT number 2 b. ASCCII c. CCITT number 5 d. EBCDIC
64. A signaling method relating to a multiplicity of circuits is conveyed over a single channel by labeled messages. a. code signaling b. syncronous c. common channel signaling d. asynchronous
56. The percentage of bit errors relative to a specific number of bits received; usually expressed as a number referenced to a power of ten. a. Bit error rate b. Transmission rate c. Distortion d. Parity check
65. ______ is a network operating system within several buildings in compound. a. Internet b. Novell netware c. 10BASE-t d. intranet
57. The process of one type of device imitating another via a hardware/software package. a. Conversion b. Emulation c. Imitation d. Simultation
66. What is the Nyquist sample rate for a voice input of 10 kHz? a. 10 kHz b. 20 kHz c. 30 kHz d. 40 kHz
58. A digital modulation technique that results in two different frequencies representing binary 1 and 0. a. FSK b. QPSK c. ASK d. DPSK
67. What is the minimum number of bits required in PCM code for a range of 10,000? a. 12 b. 9 c. 14 d. 8
59. One dit is equal to _____ bits. a. 3 b. 3.5 c. 3.32 d. 4
68. How many levels can be represented in PCM transmission system if the binary numbers 00000000 to11111111 are used to represent signal levels? a. 256 b. 64 4
MITRC REFRESHER COURSE Telephony c. d.
ANSWER KEY
128 512
Datacom & Digital
a. b. c. d.
69. A symbol to represent a data communications facility within the wide area network. a. Hub b. Cloud c. Server d. Gateway
LAN WAN ISDN PSTN
78. A data communications component that provides control or supporting services for other computers, terminals, or devices in a network. a. Host b. Communication controller c. Cluster controller d. Interface equipment
70. All bits in a character are sent and received _____ in serial port. a. One at a time b. Simultaneously c. In group of 2 bits d. In group of 3 bits
79. Which data network configuration let computers share their resources? a. Peer to peer b. Hierarchical c. PVC d. LAN
71. Message switching is ____ network. a. Hold and forward b. Forward c. Hold d. Store and forward
80. A means of improving the quality of a private-line circuit by adding amplifiers and equalizer to it. a. Line equalizer b. Line amplifying c. Line conditioning d. Line encoding
72. Packet switching is _____ network a. Hold and forward b. Forward c. Hold d. Store and forward
81. Direct distance dialing (DDD) network is commonly called a. Private-line network b. PT network c. Dial-up network d. Trunk network
73. Polling is an invitation by the primary to secondary equipment to ____ a message. a. Store b. Receive c. Transmit d. Read
82. A type of server that allows multiple users to take advantage of a single printing device. a. Print b. Client c. Network d. File
74. An 8-bit character code. a. EBCDIC b. BAUDOT c. ASCII d. HOLLERITH
83. _____ ensures that the transmitter and the receiver agree on a prescribed time slot for the occurrence of a bit. a. Bit or clock synchronization b. Modem or carrier synchronization c. Character synchronization d. Message synchronization
75. Equipment that interfaces the data terminal equipment to the analog transmission line. a. Modem b. Muldem c. Multiplexer d. Codec
84. Characters that must be transmitted other than data are called a. Parity b. Error c. Overhead d. Hamming bits
76. A communication network design for transferring data from one point to another a. Public Telephone network b. Public Data network c. Value Added Network d. Packet Switching network
85. The generating power polynomial x7 + x5 + x4 + x2 + x1 + x is equivalent a. 101101110 b. 101101111
77. A conceptual network in which all transmission lines handle digital or digitalized data. 5
MITRC REFRESHER COURSE Telephony c. d.
Datacom & Digital
010010001 10110111
b. c. d.
Digital transmission Base band transmission Analog transmission
86. A central device into which each node of a star network is directly connected a. Hub b. Central pointer c. Router d. Repeater
95. Which is considered as the fastest LAN topology? a. Ring b. Bus c. Star d. Tree
87. To ____ is to send a file to a remote computer. a. Upload b. Download c. Call d. Transmit
96. What is the most widely used data communications code? a. Gray b. EBCDIC c. Baudot d. ASCII
88. A microcomputer attached to a network requires a a. NIC b. RS 232 c. Software d. Protocol
97. Mark and space refer respectively to a. 1 and 0 b. Dot and dash c. Message and interval d. On and off 98. What is the other name for parity? a. BCC b. LRC c. VRC d. CRC
89. Digital telephones and integrated voice-data workstations are examples of what type of ISDN equipment? a. TE b. TA c. NT2 d. TP
99. A device that performs routing functions and protocol translation from one network to another. a. Gateway b. Bridge c. Router d. Repeater
90. How many OSI layers are covered under the X.25 standard? a. 3 b. 4 c. 7 d. 2
100. Not important characteristic of the physical layer a. Electrical b. Mechanical c. Logical d. All of them
91. With _____, a station monitors the line to determine if the line is busy. a. CSMA/CD b. CSMA/CA c. Token Passing d. PDDI
. 92. CCITT standard concentrating on data communications over the telephone network. a. V series b. X series c. I series d. T series 93. Broadband uses a. TDM b. Space multiplexing c. FDM d. Statistical multiplexing 94. _____ uses the connecting medium as a single-channel device. a. Broadband transmission 6
