Panko – Chapter 5 – Wireless Lans – Flashcards
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What is the Golden zone in commercial mobile radio transmission?
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The zone where the frequencies flow from high MHz to low GHz
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Do WLANs today use licensed or unlicensed bands?
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Unlicensed
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3 What are the disadvantages of unlicensed bands
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No way to stop interference from other nearby users Your only recourse is to negotiate with others
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In what two unlicensed bands does 802.11 operate
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2.4GHz and 5 GHz
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How many non-overlapping channels does the 2.4 GHz band support
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3
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How wide are 802.11 channels usually
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20 MHz
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How many nonoverlapping channels does the 5 GHz band support
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11-24
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In unlicensed bands what type of transmission method is required by regulators
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Spread spectrum transmission (SST)
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What do the following stand for: FHSS = DSSS = OFDM =
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Frequency Hopping spread spectrum Direct sequence spread spectrum Orthogonal Frequency division multiplexing
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What spread spectrum transmission method is used in 54 Mbps 802.11g WLANs
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Orthogonal frequency division multiplexing (OFDM)
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When there is an access point and several wireless hosts, why may only one device transmit at a time?
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The access point and all of the wireless hosts transmit and receive in a single channel - meaning that only one transmit at a time and the other devices must wait.
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Is a wireless access point a bridge or a router
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Router
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What does CSMA/CA + ACK stand for?
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Carrier sense multiple access with collision avoidance (CSMA/CA) Acknowledgement frame (ACK)
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What is the purpose of the ACK
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When a host receives a frame from an access point, or when a wireless access point receives a frame from a host, the receiver immediately sends an acknowledgement frame known as the ACK.
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14 What are the rated speads for 802.11a, b, g, n
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802.11: 2 Mbps 802.11a: 54 Mbps 802.11b: 11 Mbps 802.11g: 54 Mbps 802.11n: 100 Mbps to 300 Mbps
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For what radio band or bands does the 802.11n standard work
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Unlicensed 2.4 GHz and 5 Ghz with OFDM+MIMO Spread Spectrum Methods
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16 What was the first widely used 802.11 LAN standard
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802.11b
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What is an evil twin access point
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Drive-by hacker sets up an access point outside walls of firm Evil twin intercepts authentication credentials, associates with real access point Decrypts message traffic, reads it, re-encrypts it, passes it on to a legitimate access point.
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18 When 802.11 was created what security protocol did it offer? What does this acronym stand for?
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WEP, wired equivalent privacy
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19 What does the Wi-Fi Alliance call 802.11i?
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WPA2
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What does the Wi-Fi Alliance call 802.11x?
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Enterprise mode
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Why is centralized access point management desirable?
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Keep management labor costs under control
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22 Why are bluetooth application profiles attractive
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Long battery life Has application profiles which designed to follow devices to work together automatically, with little or no user intervention
