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120 Cards in this Set
- Front
- Back
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When an antenna receives RF signals, the time differential between the main signal and the reflected signal is known as what?
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Delay spread
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What are the 4 possible results of multipath?
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Upfade, downfade, nulling, and data corruption
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What are the 2 types of gain (Amplification)?
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Active
Passive |
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What are the 3 possible results of VSWR?
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Decreased Amplitude
Erratic signal strength Transmitter failure |
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Name the most common device that creates passive gain.
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Antenna
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What is the passive gain of antennas typically compared to?
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An isotropic radiator
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All the components of a system including a transmitter, cabling and amplifilers up to but not including the antenna is know as the _______.
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Intentional radiator
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What is the term that describes the amount of power that leaves the head of the antenna?
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Equivalent isotropically radiated power (EIRP)
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Name some absolute measurements of power.
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Watt (W)
milliwatt (mW) dBm |
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Which absolute measurement of power references decibels to 1 mW?
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dBm
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Which relative measurement of power is referenced to an isotropic radiator?
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dBi
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Which relative measurement of power is referenced to dipole antenna?
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dBd
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How much will absolute power increase with +3 dB of gain?
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2 times
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How much will absolute power increase with +10 db of gain?
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10 times
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What are the 3 major types of antennas?
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Omnidirectional
Semi directional Highly directional |
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What are the 2 types of Omnidirectional antennas?
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Low gain
High gain |
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What are the major types of semidirectional antennas?
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Yagi
Planar (Patch or panel) Sector |
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What are the major types of highly directional antennas?
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Parabolic dish
Grid antenna |
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How much of the Fresnel zone must be clear for reliable communications in an outdoor PtP bridge link?
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60 % minimum
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After a distance of how many miles must you increase antenna height due to the natural curvature of the earth, assuming little elevation differences between 2 points?
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7 Miles
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What term describes the process of 2 antennas sampling the received signal, looking for the best signal?
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Antenna diversity
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What term describes the forward loss of power due to reflected voltage?
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Return loss
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Voltage standing wave ratio (VSWR) is a ratio comparing which 2 measurements?
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Impedence, mismatch, perfect impedence
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What is the standard unit of measurement of electrical resistance?
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Ohm
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What is a common mounting fastener used when installing antennas?
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U-bolt
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Name some considerations when purchasing antenna accessories.
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VSWR rating
Impedence Frequency response Max input power insertion loss, connector type, antenna gain signal pattern |
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What is needed to connect a standard connector to a proprietary connector?
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Pigtall cable or connector series adapter
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True or False: Lighting arrestors will protect equipement from direct lighting strikes.
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FALSE
Lighting arrestors will not protect equipment from direct lighting strikes but may protect equipment from damage due to transient currents. |
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What types of antennas can be used for long distance point-to-point bridge links?
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Highly directional parabolic dishes and grid antennas
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Name a situation where a splitter might be used.
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Although not recommended, a splitter may be used with a sectorized antenna array in a point-to-mulitipoint bridge base station. A splitter shoild only be used when designed by the manufacturer as part of the antenna system.
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A_______signal is a signal where the bandwidth is wider than what is required to carry the data.
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Spread Spectrum
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A narrowband signal is charactrized by ___ frequency and ___ amplitude.
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Narrow
Strong |
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A spread spectrum signal is characterized by ___ frequency bandwidth and ___ amplidude.
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Wide
Low |
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What is the term that describes the period when an FHSS radio card moves between carriers?
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Hop time
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What is the term that describes the period when an FHSS radio card is transmitting on a specific frequency?
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Dwell time
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What is the frequency range that the IEEE designates for frequency hopping transmission for 802.11 class 14 FHSS radios?
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2.402 - 2.48 GHz, 79 MHz wide
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How ide are the DSSS channels in the 2.4 GHz ISM band?
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22 MHz
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How much theoretical frequency separation is there between channels 6 and 11?
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3 MHz
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The original 802.11 standard required how much separation between the center frequencies for DSSS channels to be considered nonoverlapping?
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30 MHz
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The 802.11b amendment required how much separation between the center frequencies for HR-DSSS channels to be considered nonoverlapping?
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25 MHz.
The 802.11b amendment is now part of the 802.11-2007 standard. |
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The 802.11g amendment required how much separation between the center frequencies for ERP-DSSS channels to be considerednonoverlapping?
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25 MHz.
The 802.11g amendment is now part of the 802.11-2007 standard. |
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The original 802.11g standard required how much separation between the center frequencies for ERP-OFDM channels to be considered nonoverlapping?
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25 MHz.
The 802.11g amendment in now part of the 802.11-2007 standard. |
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The original 802.11a standard required how much separation between the center frequencies for OFDM channels to be considered nonoverlapping?
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20 MHz
The 802.11a amendment in now part of the 802.11-2007 standard. |
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True or False:
ERP-OFDM is more resistant to multipath than HR-DSSS |
True
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True or False:
HR-DSSS is less susceptible to narrowband interference than FHSS. |
False
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An OFDM channel has ___ subcarriers, of which ___ are used for transmitting data.
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52, 48
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Which RF technology uses convolution coding and forward error correction?
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OFDM - Orthogonal Frequency Division Multiplexing
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The 3 original 5 GHz UNII bands use ___ wide, and each has ___ channels.
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100 MHz, 4
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Carrier Sense Multiple Access w/Collision Avoidance (CSMA/, the aggregate throughput is typically ___ percent or less of the actual data rate.CA)
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50
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What term describes a wireless computer network used for communication between computer and peripheral devices within close proximity to each other?
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Wireless personal area network (WPAN)
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True or False:
The 802.11 standard defines wireless wide area networking |
False:
The 802.11 standard defines WIRELSS local area network |
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What term best describes the logical name of an extended service set (ESS)?
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Service set identifier (SSID) or extened service set identifier (ESSID)
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What are the service sets defined by the 802.11-2007 standard?
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Basic service set (BSS)
Extended service set (ESS) Independent basic service set (IBSS) Quality-of-service basic service set (QBSS) |
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Which term describes one or more access points connected by a distribution system medium?
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Extended service set (ESS)
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Which term describes 2 or more client stations using peer-peer commnications w/o and access point?
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Independent basic service (IBSS)
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What is a basic service set identifier (BSSID)?
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The MAC layer identifier of a basic service set (BSS) or an indepentent basic service set (IBSS)
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What is a network name comparable to a Windows workgroup name that is used to describe a WLAN?
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Service set identifier (SSID)
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Ho much cell coverage overlap is needed for wireless repeaters?
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50 %
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What are the 2 possible configuration modes for a client station?
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Infractructure
Ad Hoc |
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What are the 2 other names for an independent basic service set (IBSS)?
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Ad hoc and peer-to-peer
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What is the term that describes access points using wireless backhaul?
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Wire Distribution system (WDS)
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How many MAC addresses are in the L2 header of a WDS frame?
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4
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What value must the network allocation vector (NAV) have before an 802.11 radio can contend for the medium?
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Zero
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What are the 2 tyoes of carrier sense?
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Virtual and physical
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What is another name for the physical carrier-sense?
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Clear channel assessment (CCA)
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What is another name for virtual carrier-sense?
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Network allocation vector (NAV)
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What is the medium access method where all 802.11 radio cards randomly access the medium with no priority?
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Distributed Coordination Function (DCF)
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What is the medium access method where the access point temporaily takes control of the medium and polls client stations?
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Point Coordination Function (PCF)
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True or False:
An independent basic service set (IBSS) can operate in PCF mode. |
FALSE
Point Coordination Function (PCF) requires an access point for polling |
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Which device is the point coordinator during PCF mode?
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Access point
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What are the 3 major 802.11 frame types?
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Management
Control Data |
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Which frame is used during passive scanning?
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Beacon
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Which frames are used during active scanning?
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Probe request and probe response
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What is some of the information that is in a beacon frame?
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Timestamp, SSID, channel, service set capabilities, spread spectrum parametersets, traffic indication map (TIM), supported data rates, proprietary information.
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Name 2 major differences between beacon and probe response frames.
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Beacons are broadcast frames, while probe response frames are unicast Beacons contain the traffic indication map (TIM), while probe response frames do not
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What are 2 methods of authentication that are defined by the original 802.11 standard
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Open System and Shared Key
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Which authentication method requires the usage of a static WEP key?
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Shared Key
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Which authentication method is the greater security risk: Open System or Shared Key?
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Shared Key. Because the challenge phrase is transmitted in cleartext followed by the same phrase using the static encryption key.
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What are the 3 states for an 802.11 station?
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Unauthenticated unassociated
authenticated unassociated authenticated associated |
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Which frame is used by a client station to initiate the roaming process?
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Reassociation request frame
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Which 802.11 frame is used by all stations to verify the delivery of a unicast frame?
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Acknowledgement (ACK)
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What is the process that allows for both HR-DSSS and ERP stations to be able to coexist and transmit within the same BSS?
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Protection mechanism
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What 2 methods can be used by the protection mechanism?
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RTS/CTS and CTS-to-self
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What frame exchanges process can be used by a station to reserve the medium?
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RTS/CTS
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What are the 2 configurable client station power-management mode?
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Active mode (also known as Continuous Aware mode)
Power Save mode |
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What are the 2 states that a client in Power Save mode can alternate between?
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Awake and Doze
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What is the field in the beacon frame that contains information about buffered unicast traffic for stations in Power Save mode?
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Traffic Indication Map (TIM)
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How do client stations tell the access point to buffer their traffic?
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Power management bit
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What frame is used for power management basic services set (IBSS)?
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Announcement Traffic Indication Message (ATIM)
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What information in a beacon is used to ensure that all stations in Power Save mode are awake at the same time to receive buffered broadcast and or multicast traffic?
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Delivery Traffic Indication Message (DTIM)
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What frame is used by Power Save mode stations in awake state ro request delivery of a buffered unicast frame from the access point?
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Power-Save-Poll (PS-Poll) frame
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What is the Wi-Fi Alliance's certification for Quality of Service (QOS) in an 802.11 envirornment?
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Wi-Fi Multimedia (WMM)
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What was the IEEE amendment for quality of service (QOS)?
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IEEE 802.11e, which is now part of the 802.11-2007 standard.
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Name some common radio card physical formats.
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Compact flash
Secure Digital PCMCIA Mini PCI Express card |
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What 2 components must be installed when installing a client station adapter?
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Driver and client software utility
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What can be used to manage multiple fat autonomous access points from a centralized location?
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Wireless network management system (WNMS)
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What can be used to manage multiple WLAN controllers from a centralized location?
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Wireless network management system (WNMS)
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How many root bridges are there in a point-to-multipoint bridge line?
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One
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What type of device can be used to segment multiple autonomous access points from the protected wired network infrastructure and provide RBAC mechanisms?
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Enterprise wireless gateway )EWG)
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What term describes a wireless device with separate routed interfaces that typically is used to provide shared Internet access in a SOHO environment?
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Residential Wireless Gateway (RWG)
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What type of wireless device uses proprietary layer 2 routing protocols?
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Wireless mesh router
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What type of PoE device can use only wired pairs 4/5 and 7/8 to cary power?
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Midspan
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What type of PoE device can use either the unused pairs or the data transmission pairs to carry power?
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Endpoint (also know as endspan)
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What is the IEEE PoE standard
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802.3-2005 clause 33 (Formerly 802.3ag)
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At what segment of the 3-tier network topology model do 802.11 WLanss typically operate?
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Access layer
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What is an example of 802.11 wireless communications being used at the distribution layer?
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Bridging
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How many access ppoints can be colocated in the 2.4 GHz ISM band without causing RF interference with each other?
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A maximum of 3
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What is an example of 802.11 wireless communications being used for last-mile data delivery?
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Wirless Internet Service Provider (WISP)
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What term describes the upshifting and downshifting of data rates by a client station between concentric zones of bandwidth?
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Dynamic rate switching (DRS)
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What type of solution is needed when roaming between layer 3 boundaries?
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Mobile IP or proprietary 3 roaming solution
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When a station accidentally transmit at the same time as other stations because it can't hear the other stations' transmissions, that station is known as a ___ node.
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Hidden
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What can be done to fix the hidden node problem?
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Use RTS/CTS to diagnose the problem.
Move the hidden node increase poer to all stations, remove the obstacle reposition the access point or add another access point |
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What can be done to fix the near/far problem?
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Decrease power to the near station
Increase power to the far station Move the remote station closer to the access point or Add another access point |
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What can cause the hidden node problem?
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Obstructions
Large coverage cells Distributed antenna systems (DASs) |
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Which tenology is the most resistant to narrowband and interference:
FHSS DSSS OFDM |
FHSS
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Bluetooth causes which type of interference?
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All-Band
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Multipath causes which type of interference?
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Intersymbol interference
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Name some factors that can affect throughput.
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CSMA/CA, Encryption, application use, number of associated clients, protection mechanism, and interference.
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Name some factors that can affect range.
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Transmission power, antenna gain, wavelength, free space path loss, and the physical enviornment.
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Name some weather elements that can affect an outdoor bridge link.
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Air stratification, rain, and wind.
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