A modem is connected in between a telephone line and a
1.network
2.computer
3.serial port
4.communication adapter
A modem that is attached to the telephone system by jamming the phone's handset into two flexible receptacles in the coupler?
1.bridge
2.gateway
3. acoustic coupler
4. time-division multiplexer
A repeater takes a weakened or corrupted signal and ............... it.
1.Amplifies
2.Regenerates
3.Resample
4.Reroute
How many carrier frequencies are used in QPSK?
1.2
2.1
3.0
4.None of the above
If the baud rate for a 64-QAM signal is 2000, what is the bit rate?
1.300
2.400
3.1000
4.12000
In a synchronous modem, the digital-to-analog converter transmits signal to the
1. terminal
2.equalizer
3.modulator
4.demodulator
In ________, the phase of the carrier is varied to represent two or more different signal elements. Both peak amplitude and frequency remain constant.
1.ASK
2.PSK
3.FSK
4.QAM
Period is the inverse of
1.Frequency
2.Phase
3.Amplitude
4.Signals
Repeater operates in which layer of the OSI model
1.Physical Layer
2.Network Layer
3.Data link Layer
4.Transport Layer
Repeaters are often used on an 802.3 network to help strengthen the signals being transmitted. As with the length of segments and the number of segments, a limit exists as to how many repeaters can be used between any two nodes. What is the maximum number of repeaters that can be used?
1.1
2.4
3.9
4.12
The black and white TV is an example of
1.non periodic composite signal
2.periodic composite signal
3.periodic simple signal
4.None of the above
The constellation diagram of BPSK has ______ dots.
1.2
2.1
3.0
4.None of the above
The _____ layer is the layer closest to the transmission medium.
1.network
2.physical
3.transport
4.data link
This kind of data transmission allows data to be transmitted in both directions on a signal carrier at the same time.
1.full-duplex
2.duplex
3.half-duplex
4.All of the above
A constellation diagram shows us the __________ of a signal element, particularly when we are using two carriers (one in-phase and one quadrature).
1.amplitude and phase
2.amplitude and frequency
3.frequency and phase
4.None of the above
A devices that links two homogeneous packet-broadcast local networks, is
1.hub
2.bridge
3.repeater
4.gateway
A form of modulation In which the amplitude of a carrier wave is varied in accordance with some characteristic of the modulating signal, is known as
1.Aloha
2.modem
3. Angle modulation
4. Amplitude modulation
A modulator converts a _____ signal to a(n) _____ signal.
1.digital; analog
2.analog; digital
3.PSK; FSK
4.FSK; PSK
A smart modem can dial, hang up and answer incoming calls automatically. Can you tell who provides the appropriate instruction to the modem for this purpose?
1.Telecommunications
2.Error detecting protocols
3.Communications software
4. Link access procedure (LAP)
Analog-to-analog conversion is needed if the available bandwidth is _______.
1.low-pass
2.band-pass
3.either (a) or (b)
4.neither (a) nor (b
Computers cannot communicate with each other directly over telephone lines because they use digital pulses whereas telephone lines use analog sound frequencies. What is the name of the device which permits digital to analog conversion at the start of a long distance transmission?
1.Modem
2.Interface
3.Attenuation
4.Teleprocessor
Demodulation is a process of
1.performing data description
2.converting analog to digital signals
3.converting digital to analog signals
4.multiplexing various signals into one high speed line signals
Demodulation is the process of
1.converting digital signals to analog signals
2.converting analog signals to digital signals
3.dividing the high-speed signals into frequency bands
4.combining many low speed channels into one high speed channel
Devices on one network can communicate with devices on another network via a
1.gateway
2.file server
3.utility server
4. printer server
For connecting modem, a computer must be equipped with a port that conforms to the RS-232 standard of the Electronic Industries Association of America. What do the letters 'RS' stand for?
1.Registered source
2.Random sequence
3.Recognised standard
4.Recommended standard
Given an AM radio signal with a bandwidth of 10 KHz and the highest-frequency component at 705 KHz, what is the frequency of the carrier signal?
1.700 KHz
2. 705 KHz
3. 710 KHz
4. Cannot be determined from given information
How many carrier frequencies are used in BASK?
1.2
2.1
3.0
4.None of the above
How many carrier frequencies are used in BFSK?
1.2
2.1
3.0
4.None of the above
If communication software can be called the "traffic cop" of a micro communication system, then what should the modem be called?
1.Link
2.Park
3.Bridge
4.Interface
If communication software can be called the "traffic cop" of a micro communication system, then what should the modem be called?
1.Link
2.Park
3.Bridge
4.Interface
If the bit rate for a 16-QAM signal is 4000 bps, what is the baud rate?
1.300
2.400
3.1000
4.1200
In _____ transmission, the carrier signal is modulated so that its amplitude varies with the changing amplitudes of the modulating signal.
1.AM
2.PM
3.FM
4.none of the above
In _____ transmission, the frequency of the carrier signal is modulated to follow the changing voltage level (amplitude) of the modulating signal. The peak amplitude and phase of the carrier signal remain constant, but as the amplitude of the information signal changes, the frequency of the carrier changes correspondingly.
1. AM
2.PM
3.FM
4.None of the above
In _____ transmission, the phase of the carrier signal is modulated to follow the changing voltage level (amplitude) of the modulating signal.
1.AM
2.PM
3.FM
4.None of the above
In _______, the peak amplitude of one signal level is 0; the other is the same as the amplitude of the carrier frequenc
1.PSK
2.OOK
3.FSK
4. none of the above
In _________, the frequency of the carrier signal is varied to represent data. Both peak amplitude and phase remain constant.
1.ASK
2.PSK
3.FSK
4.QAM
Interconnected networks need communication processors such as switches, routers, hubs, and gateways. Select the best fit for answer:
1.TCP/IP
2.Protocol
3.Open Systems
4. Internetwork processor
MAC address is also known as __________.
1.Hardware address
2.Physical address
3. IP address
4.both and b above
Now-a-days computers all over the world can talk to each other. Which is one of the special accessories essential for this purpose?
1.Fax
2.Modem
3.Scanner
4.Keyboard
Propagation time is equals to
1.Distance/Propagation speed
2.Propagation speed/Bandwidth
3.Message size/ Bandwidth
4.Bandwidth/Queuing time
Quadrature amplitude modulation (QAM) is a combination of ___________.
1.ASK and FSK
2.ASK and PSK
3.PSK and FSK
4.None of the above
Repeater function in the ...................... layer.
1. Physical
2.Data link
3.Network
4.None of These
RS-449/442-A/423-A is
1.the ratio of the number of data units in error to the total number of data units
2. a set of physical layer standards developed by EIA and intended to replace RS-232-C
3.a check bit appended to an array of binary digits to make the sum of the all the binary digits
4.a code in which each expression conforms to specific rules of construction, so that if certain errors occur in an expression the resulting expression will not conform to the rules of construction and
The cheapest modems can transmit
1.100 bits per second
2.300 bits per second
3.600 bits per second
4.900 bits per second
The cheapest modems can transmit
1.100 bits per second
2.300 bits per second
3.600 bits per second
4.900 bits per second
The constellation diagram of 16-QAM has ______ dots.
1.4
2.16
3.8
4.None of the above
The constellation diagram of BASK has ______ dots.
1.2
2.1
3.0
4.none of the above
The constellation diagram of QPSK has ______ dots.
1.2
2.1
3.4
4.None of the above
The Federal Communications Commission (FCC) allows ______ kHz for each FM station.
1.20
2.100
3.200
4.None of the above
The Federal Communications Commission (FCC) allows ______kHz for each AM station.
1.5
2.10
3.20
4.None of the above
The fundamental requirements of private-to-public network interconnection methods which need to be provided in gateways is/are
1.adequate cost control mechanisms for administration of the private networks
2.universal accessibility for private network Data Terminal Equipment (DTE) c.
3.both (a) and (b)
4.to assign address to private network DTEs
The level of the signal is inversely proportional to the
1.Reliability of a system
2.Efficiency of a system
3.Accuracy of a system
4.Bandwidth of a system
The Nyquist formula gives us any signal level while Shannon capacity gives us the
1.Lower Limit
2.Upper Limit
3.Specific signal level
4.Both (a) and (b)
The physical layer, in reference to the OSI model, defines
1.the virtual circuit interface to packet-switched service
2.the interface between the X.25 network and packet mode device
3.data link procedures that provide for the exchange of data via frames that can be sent and received
4.All of the above
This kind of data transmission allows data to be transmitted in both directions on a signal carrier at the same time.
1.full-duplex
2.duplex
3.half-duplex
4.All of the above
What device separates a single network into two segments but lets the two segments appear as one to higher protocols?
1.Switch
2.Bridge
3.Router
4.Gateway
What is the difference between a switch and a hub?
1.Switches operate at physical layer while hubs operate at data link layer
2.Switches operate at data link layer while hubs operate at transport layer
3.Switches operate at data link layer while hubs operate at physical layer
4.Switches operate at transport layer while hubs operate at physical layer
What is the main function of DSLAM?
1.Convert analog signal into digital signal
2.Covert digital signal into analog
3.Used in router to detect the loss packets
4.None of the above
What is the name of the device that connects two computers by means of a telephone line?
1.cable
2.bus
3.Tape
4.modem
What is the name of the device that converts computer output into a form that can be transmitted over a telephone line?
1.Modem
2.Teleport
3.Multiplexer
4.Concentrator
What is the use of Bridge in Network?
1.to connect LANs
2.to separate LANs
3.to control Network Speed
4.All of the above
Which of the following allows devices on one network to communicate with devices on another network?
1.modern
2.gateway
3.t-switch
4.multiplexer
Which of the following connectivity devices is used to extend a network on a purely mechanical basis?
1.Active hub
2.Gateway
3.Router
4.Switch
Which of the following device copies electrical signals from one Ethernet to another?
1.hub
2.bridge
3.repeater
4.passive hub
Which of the following device is used to connect two systems, especially if the systems use different protocols?
1.hub
2.bridge
3.gateway
4.repeater
Which of the following is not a digital-to-analog conversion?
1.ASK
2.PSK
3.FSK
4.AM
Which of the following is not an analog-to-analog conversion?
1.AM
2.PM
3.FM
4.QAM
Which of the following is not the possible ways of data exchange?
1.Simplex
2.Multiplex
3.Half-duplex
4.Full-duplex
Which of the following is used for modulation and demodulation?
1.modem
2.gateway
3.protocols
4.multiplexer
Which of the following layer decide the transmission rate in a Network?
1.Physical layer
2.Data link layer
3.Network layer
4.Transport layer
Which of the following statements is correct?
1.characteristic of LAN is unlimited expansion
2. characteristic of LAN is low cost access for low bandwidth channels
3. characteristic of the hub architecture of ARC-net is alternative routing
4. characteristic of the hub architecture of ARC-net is directionalized transmission
Who invented the modem?
1.AT & T Information Systems, USA
2.Digital Equipment Corpn.
3.Wang Laboratories Ltd.
4.Apple Computers Inc.
_____ conversion is the representation of analog information by an analog signal.
1.Digital-to-analog
2.Analog-to-analog
3.Analog-to-digital
4.Digital-to-digital
______ conversion is the process of changing one of the characteristics of an analog signal based on the information in the digital data.
1.Digital-to-analog
2.Analog-to-analog
3.Analog-to-digital
4.Digital-to-digital
________ uses two carriers, one in-phase and the other quadrature.
1.ASK
2.PSK
3.FSK
4.QAM