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Wireless Networking

Brian Nichols Information Technology Englisch 90 Karten

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  1. 1What is a wireless networkAny network where information is transmitted wirelessly
  2. 2Name 3 things that wireless communication uses ? & What are they examples ofRadio waves
    Microwaves
    Free-space optical communications
    Examples of:
    Electro-magnetic waves
  3. 3What are electromagnetic waves characterized by?Their frequency & wavelength
  4. 4Higher frequencies will attenuate (weaken) more than lower frequencies.True
  5. 5How can we modulate a radio wave?By changing either amplitude or its frequency
  6. 6in the lab (T115), which VLAN does your AP use to communicate with its controller?vlan X0
  7. 7How many Access Points (maximum) can a client device be associated to?One
  8. 8What is the range of frequencies measured in?Bandwidth
  9. 9Passive scanning is faster than active scanning.False
  10. 10Name the 5 types of wireless networksPAN (Personal Area Network)
    LAN (Local Area Network)
    Mesh network
    MAN (Metropolitan Area Network)
    Global Area Network
  11. 11What is a Wireless PAN (Personal Area Network) and give an exampleCentered around an individual and the range is typically a few meters.
    An example is Bluetooth
  12. 12What does a Wireless LAN (Local Area Network) require?*Wireless Access Point
    *Wireless Client
  13. 13What is a Wireless Mesh networkIt Doesn't require an infrastructure to operate, although it may have a connection to a fixed network.
    It Requires Ad Hoc and mesh routing capabilities
  14. 14What is a Wireless MAN (Metropolitan Area Network)Is a connection of several wireless LANs over an area the size of a city
  15. 15What is a global Area NetworkWhen Computers and Local Area Networks, using wireless connectivity, connect to form a bigger network.
  16. 16What is a major issue with global Area NetworksA major issue is handover from one local coverage area to the next
  17. 17What is an autonomous access pointThe base station for the network. They normally act as routers and as connections to a fixed wired network.
  18. 18What is a wireless clientA device with a wireless network interface
  19. 19What are the differences between a BSSID and a SSID?A BSSID is the Basic Service Set Identifier. It is the MAC address of the Access Point.
    A SSID is an ‘informal’ name for a BSS, and can be chosen by the AP administrator. A BSS has one AP.
  20. 20What are, and what is the relationship between, a BSS and an ESS?A BSS is a Basic Service Set – an Access Point and its connected devices.
    A ESS is an Extended Service Set.
    An ESS is a set of connected BSSs that share the same SSID, security, and DS (distribution system). A device sees all APs in a ESS as single BSS.
  21. 21When using extended service set (ESS) are devices able to roam between AP's without interrupting communicationsYes
  22. 22What is the difference between ad hoc and infrastructure mode in wireless networking?In ad hoc mode there is no access point and devices communicate directly with each other. The SSID of the network is chosen by the client that ‘starts’ the network and it is broadcast in turn by a randomly chosen member of the network.
    In Infrastructure mode devices are all clients, which then connect to dedicated Access Points.
  23. 23What is Wi-Fi DirectWi-Fi Direct is a Wi-Fi standard enabling devices to easily connect with each other without requiring a wireless access point
  24. 24What are the two types of roaming in Wi-Fi networks and what do they doInternal roaming - Clients move from one AP to another in the same ESS when the first AP becomes too weak
    External roaming - Client moves into another WLAN, typically from a different provider & the client must have software installed to ensure sessions persist, so no loss of communications, during the transfer
  25. 25When radio signals overlap, what 3 issues can be the result? & How can you prevent them?*Loss of data
    *Reduced performance
    *Total loss of connectivity
    &
    By making sure that adjacent base stations do not operate on the same frequency
  26. 26What is DCF? What are the steps for transmission?Distributed Coordination Function
    1) Listen for a clear channel (NAV timer)
    2) Wait for my turn (Contention window slot)
    3) Transmit/talk(retry on collision)
  27. 27What encryption and integrity protocols were used with WEP, and why are these a problem in modern networks?RC4 was used for encryption & CRC32 was used for integrity
  28. 28Why is physical layer security so important on a wireless network?Wirless is an open medium so anyone can capture data packets, unlike a wired network where some effort has to be made to tap the cable.
  29. 29What is Wi-Fi Protected Setup and why is it weak?Wi-Fi Protected Setup enables users to easily setup wireless communications using WPA or WPA2 with a secure pre-shared key (secret).
    &
    It is weak as the pin can be brute force discovered by an attacker and obtain the pre-shared key.
  30. 30What is the relationship between WEP, WPA and WPA2?WEP uses the secret key + IV and a RC4 algorithm to achieve security
    WPA was a half-way house between WEP and WPA2. It solved the problems of WEP by replacing the simple key generation (secret key + IV) with the Temporal Key Integrity Protocol (TKIP).
    WPA2 implements the mandatory requirements of the current security standard for WLANs. It replaces RC4 with AES
  31. 31How do some APs prevent issues with WPSBy slowing or disabling the PIN method after a specified number of failed connections
  32. 32What is? Velocity Frequency WavelengthVelocity - The speed in a given direction
    Frequency - Number of cycles per second
    Wavelength - Distance travelled in one cycle
  33. 33Passive scanning is faster than active scanning.False
  34. 34Which frequency has the shortest wavelength?5GHz
  35. 35The Aruba Wireless Controller is what type of network device?L3 Switch
  36. 36What CLI command is used to reset a controller to factory default?write erase
  37. 37How many VLANs did you create on the controller??
  38. 38Which of the following best describes a configuration profile as used by Aruba Controllers?A profile is a segment of configuration for a specific sub-function. Profiles generally have a hierarchical relationship.
  39. 39Where are the tunnel end-points (IP Interfaces) of the GRE Access Tunnel?Access Point
    Wireless Controller
  40. 40How many VAPs may be contained in an AP Group?1 or more...
  41. 41How many SSID Profiles may be contained in a VAP Profile?One
  42. 42How many radios does your AP have?Two
  43. 43How many of the channels in the 2.4 GHz band should be used?Three
    1, 6, 11
  44. 44How many bytes is a BSSID?Six (6) bytes
    or
    48 bits
  45. 45How many APs are there in an Independent Basic Service Set (IBSS)?Zero (0)
  46. 46A _______________ determines which WLAN you are connected to.SSID
  47. 47How many APs are there in a Basic Service Set (BSS)?One
  48. 48In the lab (T115) we are using Autonomous Access Points.False
  49. 49If we can generate a wave with 8 possible different amplitudes, how many bits could we transmit at the same time?Three
  50. 50Which technology is most commonly used for the Distribution System (DS)?Ethernet
  51. 51A _______________ indicates which AP you are associated (conected) to.BSSID
    MAC Address
  52. 52Which has the fastest transmission speed?802.1n 600 Mbps
    802.1 ac 6.9 Gbps
  53. 53What role is assigned to your wireless client if it fails the MAC Authentication?Logon
  54. 54Which profiles were configured inside the MAC-aaa-profile?MAC-authentication-profile
    MAC-local-server-group
  55. 55it would be a good idea for the College to use MAC authentication for its WLAN users.False
  56. 56What is the purpose of the Translation Bridge?Access Point (AP) provides translation between wireless communications and ethernet communications.
  57. 57What is CSMA/CD?CSMA/CD uses ethernet and implements collision detection for half-duplex architecture.
    As they transmit on Tx wires and listen on Rx wires, collisions are detected immediately.
  58. 58What is CSMA/CA?CSMA/CA uses wireless (802.1) and implements collision avoidance for half-duplex architecture.
    Radios can only transmit or receive at any one time.
  59. 59Possible hidden Node Solutions?Add an AP
    Remove obstacle
    Use RTS/CTS (request to send/clear to send * NOT RECOMMENDED)
  60. 60What is the purpose of the Contention Window?Prevents transmission collisions by spreading transmission attempts from multiple devices (STA) over the time interval called the Contention Window.
  61. 61What is the role of the IEEE?Development of 802.1 WLAN standards and policies
  62. 62What is the role of the Wi-Fi Alliance?Certifies that Wi-Fi products comply with standards.
    Not mandatory...
  63. 63A Local Area Network (LAN) has a coverage of how many meters approximately?50 to 100 meters
  64. 64What frequency does 802.11 a, n, ac transmit at?5 GHz
    (802.11n transmits in both 2.4 and 5 GHz)
  65. 65What frequency does 802.11 b, g, n transmit?2.4 GHz
    (802.11n transmits in both 2.4 and 5 GHz)
  66. 66What is the maximum transmission speed of 802.11a and g?54 Mbps
  67. 67What is the maximum transmission speed of 802.11ac?6.9 Gbps with a maximum of 8 MIMO Streams (antennas)
  68. 68What is the maximum transmission speed of 802.11n?600 Gbps with a maximum of 4 MIMO Streams (antennas)
  69. 69What are the steps of Controller Discovery and AP Join Process?1) AP discovers IP address of Master Controller
    2) Master Controller updates AP OS version to match Controller OS.
    3)Master Controller sends configuration info to AP.
    4) AP joins Local Controller.
  70. 70What is Passive Scanning?The device (STA) listens for a Beacon from the AP.
    Transmits at 10 times per second.
  71. 71What is Active Scanning?Device (STA) sends a probe request to AP.
    Active is the most used over Passive scanning.
  72. 72Does a client device know if it is connected to an autonomous AP or lightweight AP?No
  73. 73What would you see in the Frame Body field of a Data Frame?The layer 3 IP data.
  74. 74Are all APs in an ESS on the same channel?No, APs are configured on different channels and spaced to ensure that APs configured for the same channel do not overlap.
  75. 75Can an AP support more than one SSID?Yes
  76. 76Will a longer "wave length" have higher or lower attenuation?Lower Attenuation
    The shorter the wavelength of the wireless signal the greater the attenuation when obstructed.
  77. 77What is signal refraction?The bending of microwave signals due to temperature, pressure and water vapor in the atmosphere.
  78. 78Conversion table mW to dBm1 mW = 0 dBm
    2 mW = 3 dBm
    10 mW = 10 dBm
    25 mW = 14 dBm
    50 mW = 17 dBm
    100 mW = 20 dBm
  79. 79Representation of DS to DS0 - 0 is peer to peer
    1 - 1 os bridged network
  80. 80How many possible vlans on a layer 3 switch?49
  81. 81What is a VAP and what does it contain?VAP - Virtual Access Point
    It contains one aaa profile and one ssid profile.
  82. 82The Basic service area is defined by:BSSID
  83. 83What is a wavelength?The distance between two identical points in an RF signal (ie: the crests).
  84. 84What is the purpose of a wireless access point?To broadcast an SSID to the world
    To provide IP addressing to a wireless segment of the Internet
    To provide a wireless extension to the distribution system
  85. 85An extended service set (ESS) consists of at least two basic service sets (BSSs).True
  86. 86What happens if two waves are 180º out of phase?They cancel each other out
  87. 87Wireless bridges generally use omnidirectional antenna to create point to point connections between buildings.False
  88. 88The Basic Service Area is also known as:Cell
  89. 89A signal's amplitude represents:Frequency
  90. 90How much overlap do wireless repeaters require?50%

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Beschreibung
Lecture 16 Flash cards about wireless networking
Erstellt von
Brian Nichols
Aufrufe
71
Verlauf
  • Erstellt von Tunds · 18 Mär 2015
  • Kopiert von Brian Nichols · 25 Feb 2017
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