Chapter 6: Earth Science

25 July 2022
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White noise is also called thermal noise or ____ noise. a. crosstalk c. Gaussian b. jitter d. spike
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c. Gaussian
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Impulse noise is also known as ____. a. noise spike c. attenuation b. jitter d. crosstalk
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a. noise spike
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Typically, impulse noise is a(n) ____ burst of energy. a. digital c. binary b. analog d. logical
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b. analog
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High humidity and wet weather can cause an increase in electrical ____ over a telephone system. a. compression c. jitter b. attenuation d. crosstalk
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d. crosstalk
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To minimize the effect of echo, a device called a(n) ____ can be attached to a line. a. echo suppressor c. amplifier b. repeater d. hub
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a. echo suppressor
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____ is the result of small timing irregularities that become magnified during the transmission of digital signals as the signals are passed from one device to another. a. White noise c. Attenuation b. Jitter d. Echo
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b. Jitter d
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Causes of jitter can include electromagnetic interference, ____, passing the signal through too many repeaters, and the use of lower-quality equipment. a. coding c. compression b. sampling d. crosstalk
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d. crosstalk
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____ is not necessarily a form of error, but can indirectly lead to an increase in errors affecting the transmitted signal. a. Impulse noise c. Attenuation b. Crosstalk d. White noise
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c. Attenuation
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____ means that if the transmitting modem sends data and the data arrives garbled, the receiving modem may ask the transmitting modem to fall back to a slower transmission speed. a. Impulse negotiation c. Attenuation b. Fallback negotiation d. Downlink
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b. Fallback negotiation
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Twisted pair Category 5e/6 cable should not be longer than the recommended 100-meter (300-foot) distance when it's transmitting at ____ Mbps. a. 100 c. 500 b. 250 d. 1000
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a. 100
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Installing proper shielding on cables prevents ____. a. white noise c. attenuation b. impulse noise d. crosstalk
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d. crosstalk
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Error detection can be performed in several places within a communications model. One of the most common places is the TCP/IP ____ layer. a. network c. network access/data link b. application d. physical
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c. network access/data link
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The most basic error-detection techniques are parity checks, which are used with ____ connections. a. synchronous c. statistical b. asynchronous d. fiber-optic
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b. asynchronous
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With ____ parity, the 0 or 1 added to the string produces an even number of binary 1s. a. even c. longitudinal b. odd d. binary
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a. even
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Isolated single-bit errors occur ____ percent of the time. a. 30 to 40 c. 50 to 60 b. 40 to 50 d. 60 to 70
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c. 50 to 60
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Error bursts occur ____ percent of the time. a. 2 to 5 c. 8 to 10 b. 5 to 10 d. 10 to 20
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d. 10 to 20
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Longitudinal parity is sometimes called longitudinal redundancy check or ____ parity. a. vertical c. random b. horizontal d. binary
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b. horizontal
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The cyclic redundancy checksum (CRC) is also called ____. a. horizontal parity c. bit parity b. vertical cyclic parity d. cyclic checksum
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d. cyclic checksum
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CRC-____ is found in Ethernet LANs. a. 5 c. 32 b. 12 d. 64
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c. 32
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____ for error control is becoming a mode of operation for some modern wide area network transmission techniques. a. Returning a message c. Correcting the error b. Doing nothing d. Fixing the error
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b. Doing nothing
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____ is offered by telephone companies to transfer data over wide areas. a. RS-232 c. SSL b. EIA-232F d. Frame Relay
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d. Frame Relay
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____ cable is the medium least prone to generating errors. a. Fiber-optic c. Twisted-pair b. Coaxial d. Copper-based
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a. Fiber-optic
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____ is probably the most common form of error control. a. Do nothing b. Correct the error without retransmission c. Sending a message back to the transmitter d. Correct the error with retransmission
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c. Sending a message back to the transmitter
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____ error control is a technique usually associated with the Stop-and-wait flow control protocol. a. Stop-and-wait c. Sliding window b. Timeout d. ACK
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a. Stop-and-wait
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When working with stop-and-wait error control, the amount of time a station waits before retransmitting a packet is called ____. a. stop time c. NAK time b. ACK time d. timeout
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d. timeout
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____ is a flow control scheme that allows a station to transmit a number of data packets at one time before receiving some form of acknowledgment. a. Stop-and-wait c. Timeout b. Sliding window d. ACK window
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b. Sliding window
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With the sliding window protocol, a station that had a maximum window size of 7 could transmit only ____ data packets at one time before it had to stop and wait for an acknowledgment. a. 5 c. 7 b. 6 d. 8
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c. 7
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A ____ protocol's function is simply to inform the transmitter what piece of data is expected next. a. CRC-16 c. stop-and-wait b. CRC-32 d. sliding window
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d. sliding window
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For a receiver to be able to fix an error—in a process called ____—redundant information must be present so that the receiver knows which bit or bits are in error and what their original values were. a. forward error correction c. backward error correction b. forward error detection d. backward error detection
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a. forward error correction
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If a receiver correctly receives packets 2, 3, and 4, it will respond with a(an) ____ . a. ACK 3 c. ACK 5 b. ACK 4 d. NAK
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c. ACK 5
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If a receiver has just received one packet of data with bytes numbered 600 to 700, it will respond immediately with ____. a. an ACK of 700 c. an ACK of 800 b. an ACK of 701 d. it will not respond just yet
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b. an ACK of 701