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Flashcards

CWNA flashcards deck 2

Dustin Sanders Networking CWNA English 175 cards

Cards in this deck (175)

  1. 1What amendment standardized DCF and QoS?802.11e-2005
  2. 2What are some advancements 802.11n provided?High Throughput (HT)
    MIMO
    Frame aggregation
  3. 3What amendment standard deals with mesh networks?802.11s-2011
  4. 4What are some advancements provided by 802.11ac?Very High Throughput (VHT)
    256-QAM modulation
    MU-MIMO
    up to 8 spatial streams
    wider channels (80MHz, 160MHz)
  5. 5How is U-NII broken down into bands?U-NII-1 (Lower Band)
    100 MHz wide starts at 5.150
    U-NII-2 (Middle Band)
    100 MHz wide starts at 5.250 GHz
    U-NII-2 Extended
    255 MHz wide starts at 5.470 GHz
    U-NII-3 (Upper Band)
    125 MHz wide starts at 5.725 GHz
  6. 6How does DSSS differ from FHSS?Unlike FHSS, where the transmitter jumped between frequencies, DSSS is set to one channel. The data that is being transmitted is spread across the range of frequencies that make up the channel. The process of spreading the data across the channel is known as data encoding.
  7. 7What is spreading or chipping?The process of converting a single data bit into a sequence. The receiving radio converts, or de-spreads, the chip sequence back into a single data bit.
  8. 8what is CCKComplementary Code Keying, aids HR-DSSS
  9. 9How much separation do 5GHz OFDM channels need to be considered non overlapping?20MHz
  10. 10What's the difference between frequency bandwidth and data bandwidth?Frequency bandwidth is the bandwidth of the frequency
    data bandwidth is how much data can be sent
  11. 11Roughly what % of aggregate throughput do you get from the advertised throughput?65%
  12. 12What does CDMA (network, not protocol) stand for?code division multiple access
  13. 13What does GSM stand for?Global System for Mobile Communications
  14. 14What is the upper layer information in a wireless data frame called?MAC Service Data Unit (MSDU)
  15. 15What is an Integration Service?How 802.11 frames are translated from a wireless environment into an 802.3 wired environment
  16. 16How many MAC addresses does a frame sent over a wireless distribution system have?4
    source address
    destination address
    transmitter address
    receiver address
  17. 17What is a BSSID?layer 2 ID of each individual BSS
  18. 18What is a BSA?Basic Service Area
    The physical area of coverage provided by an access point in a BSS
  19. 19what is nomadic roaming?when WAPs don't overlap and you lose connectivity when moving around
  20. 20How does an IBSS differ from a MBSS?IBSS is a mest network made up of only clients
    MBSS is a mesh network made up of APs
  21. 21is mesh routing done by MAC addresses or IP addresses?MAC. Wireless is a layer 2 medium
  22. 22What are the 6 modes an AP can be in?Access Point mode
    Bridge mode
    Workgroup Bridge mode (backhaul)
    Repeater mode
    Mesh mode
    Scanner mode (for a WIPS)
  23. 23What are the 2 modes a client STA can be in?Infrastructure mode (normal operations, talks to AP)
    Ad Hoc mode (for IBSS)
  24. 24What is Point Coordination Function (PCF)allows for the access point (AP) to poll client stations about their need to transmit data.
    (optional)
  25. 25What are the 4 main components of DCF?Distributed Coordination Function (DCF)
    ■ Interframe space
    ■ Duration/ID field
    ■ Carrier sense
    ■ Random backoff timer
  26. 26What is Interframe space (IFS)?the period of time that exists between transmissions of wireless frames
  27. 27What are the 6 types of IFS?■ Reduced interframe space (RIFS), highest priority
    ■ Short interframe space (SIFS), second highest priority
    ■ PCF interframe space (PIFS), middle priority
    ■ DCF interframe space (DIFS), lowest priority
    ■ Arbitration interframe space (AIFS), used by QoS stations
    ■ Extended interframe space (EIFS), used after receipt of corrupted frames
  28. 28What is the duration of IFS from shortest to longest?RIFS < SIFS < PIFS < DIFS < AIFS < EIFS.
    RSPDAE
  29. 29What is Physical Carrier Sense?When a STA is not transmitting it is listening to see if medium is available
  30. 30What is a Contention Window? (CW)The range of backoff time a STA will use after a collision is detected.
  31. 31What is Enhanced Distributed Channel Access (EDCA)?An enhancement of DCF, for Qos. Puts traffic in 4 categories
    AC_BK (Background), AC_BE (Best Effort), AC_VI (Video), and AC_VO (Voice)
  32. 32What is the idea of airtime fairness?allocate equal time, as opposed to equal opportunity on the medium.
    allows older technologies to still communicate alongside newer devices, along with enabling devices to maintain communications by shifting to slower data rates as they move away from an access point. T
  33. 33What are the 3 parts of a MPDU frame?MAC header
    Frame body (MSDU)
    FCS
  34. 34What is the LLC MAC sublayer?Logical Link Control
    interface between MAC and IP layers
  35. 35What happens when the LLC sends an MSDU to the MAC sublayer?MSDU is encapsulated with MAC header info and FCS, thus all become a MPDU frame
  36. 36What 2 sublayers comprise the PHY layer?Physical Layer Convergence Procedure (PLCP)
    Physical Medium Dependent (PMD)
  37. 37What does the Physical Layer Convergence Procedure (PLCP) do?The PLCP prepares the frame for
    transmission by taking the frame from the MAC sublayer and creating the PLCP Protocol Data Unit (PPDU)
  38. 38What does the PMD sublayer do with the PPDU?modulates and transmits the data as bits
  39. 39What are the three 802.11 frame types?management
    control
    data
  40. 40What frame type is unique to 802.11 networks?Management frames
    (Beacon frames, probe responses, association requests, etc..)
  41. 41What are some examples of control frames?RTS/CTS
    ACK
  42. 42What kinds of frames are the heartbeat of a network?Beacon frames
    10 every second
  43. 43What is authentication in a wireless network?NOT USER AUTHENTICATION. It's the same as plugging in an ethernet cable into a switch. It just checks if the STA can connect to the AP.
  44. 44What does an AP send to a client after an association request?association identifier (AID)
    (grants permission to join or no)
  45. 45Who makes the decision to roam? AP or client?client
  46. 46What is RTS/CTS?Request to send/clear to send (RTS/CTS) is a mechanism that performs
    a NAV distribution and helps prevent collisions from occurring. This NAV distribution
    reserves the medium prior to the transmission of the data frame.
  47. 47If a client in a BSS is in a power save mode, what frame wakes it up to tell it that it has traffic waiting to be sent to it?DTIM
    Delivery Traffic Indication Message
  48. 48What is an MDM?Mobile Device Managment
    (think mobile iron from kershaw)
  49. 49What is a chipset?A group of integrated circuits designed to work together
  50. 50What is a wifi client utility?either what the OS of a computer uses to manage wireless, or a 3rd party program to manage the wireless
  51. 51What are the 3 functions of the Management plane?Configuration
    Monitoring/reporting
    Firmware managemt
  52. 52What is the control plane?protocols that provide the intelligence and interaction
    between equipment in a network.
  53. 53what is the data plane?location in a network
    where user traffic is actually forwarded
  54. 54What is a key feature of WLAN controllers?IP encapsulated Tunneling
    802.11 can't traverse 802.3 without tunneling like Generic Routing Encapsulation (GRE) or or CAPWAP
  55. 55What are the two types of data forwarding modes when using WLAN controllers?Centralized Data Forwarding (AP sends everything to controller to process)
    Distributed Data Forwarding
    (AP performes data forwarding locally.)
  56. 56What is a distributed WLAN architecture?No centralized WLAN controllers, data and control functions handled by AP. NMS is used for centralized management.
  57. 57What must be enabled on the 802.3 access switch to support VLANs for distributed WLAN architecture?802.1Q Trunking
  58. 58What is the goal of distributed wlan architecture and removing wlan controllers?to avoid having to forward traffic to the core
  59. 59What is a virtual AP system?multiple access points that all share a single basic service set identifier (BSSID). All handoffs handled by wlan controller
  60. 60What is RTLS?real time location services, waps used to track location of a device
  61. 61What two authentication mechanisms did 802.11-2012 standardize?PreSharedKeys
    802.1X port-based access control
  62. 62What are three concerns when it comes to BYOB?■ Making sure that the devices are capable of connecting to the network using the proper authentication
    ■ Ensuring the use of encryption protocols along with the ability for these devices to be able to smoothly roam throughout the network without losing connectivity
    ■ Providing network access, not only based upon the identity of the user of the device but also based upon the type of device or other device or connection characteristics
  63. 63What is Fixed Mobile Convergence?The goal of FMC systems is to provide a single device, with a single phone number that is capable of switching between networks and always using the lowest-cost network.
    (Think of VoIP call on smartphone moving between cell towers and wifi)
  64. 64What happens if all APs are on the same channel?unnecessary medium contention overhead occurs.
    CSMA/CA dictates half-duplex communications, and only one radio can transmit on the same channel at any given time
  65. 65what is an invaluable tool for diagnosing layer 1 802.11 issues?spectrum analyzer
  66. 66What is the mortal enemy of WLAN performance?Layer 2 retransmissions at the MAC sublayer
  67. 67What are some symptoms of layer 2 retransmission?Latency and Jitter
  68. 68what is latency?Latency is the time it takes to deliver a packet from the source device to the destination device. A delay in the delivery (increased latency) of a VoIP packet due to layer 2 retransmissions can result in echo problems.
  69. 69What is jitter?Jitter is a variation of latency. Jitter measures how much the latency of each packet varies from the average. If all packets travel at exactly the same speed through the network, jitter will be zero. A high variance in the latency (jitter) is a common result of 802.11 layer
    2 retransmissions. Jitter will result in choppy audio communications, and constant retransmissions will result in reduced battery life for VoWiFi phones.
  70. 70what is the layer 2 retransmission tolerance of most data applications?10%
  71. 71what is the layer 2 retransmission tolerance of most VoIP?2%
  72. 72What would cause layer 2 retransmissions? High SNR or low SNR?Low SNR
    (means there's not that much difference between signal and noise)
  73. 73What can mismatched power settings cause?Layer 2 retransmissions with Near/Far issue if client station is broadcasting too quietly for super loud AP to hear.
  74. 74What is a hidden node problem?When 1 AP can't be heard by the other APs, so the other APs don't know that the hidden AP is using the channel at a given time
  75. 75How can you tell if you have a hidden node issue with a protocol analyzer?If the protocol analyzer indicates a higher
    retransmission rate for the MAC address of one station when compared to the other client stations
  76. 76How can you resolve hidden node issues?Increase client transmit power
    move obstacles causing hidden node
    move hidden node
    add another AP that can heard the node
  77. 77What is DRS?Dynamic Rate Switching
    When a client moved away from an AP it will shift down to lower bandwidth capabilities
  78. 78What is the recommended overlap for good roaming?15-30% overlap at -70dBm
  79. 79What is needed if you're going to roam time sensitive applications in an 802.1x/EAP network?Fast Secure Roaming
  80. 80What protocol enables layer 3 roaming?Mobile IP.
    Mobile client address known to device on network called "Home Agent" (HA) This HA becomes the single point of contact for roaming client when roaming across layer 3 boundaries
  81. 81How does co-channel interference differ from adjacent channel interference?co-channel interference is caused by APs on the same channel, adjacent channel interference is caused by near by overlapping channels.
  82. 82What is adjusting the transit power of a AP to changed the cell size called?sizing
  83. 83how does AP load balancing work?If an AP is overloaded and a client tries to connect, the AP will defer the association request in the hopes that the client will try to connect to another AP
  84. 84At what % airtime usage is an AP considered fully burdened?80%
  85. 85What are the 5 main components to securing an 802.11 network?Data privacy and integrity
    Authentication, authorization, and accounting (AAA)
    Segmentation
    Monitoring
    Policy
  86. 86Out of Data, management, and control frames, which ones are encrypted?usually only data
  87. 87What is the AAA of security?Authentication (can a device physically connect?)
    Authorization (is a device allowed to connect?)
    Accounting (tracking the connected device)
  88. 88Are MAC filters a reliable enterprise security method?nope
  89. 89What was the intended goal of WPA-Personal?to move away from static encryption keys to dynamically generated keys using a simple passphrase as a seed.
  90. 90What is the only real difference between WPA and WPA-2?the encryption cipher. WPA-Personal
    and WPA2-Personal both use the PSK authentication method; however,
    WPA-Personal specifies TKIP/RC4 encryption and WPA2-Personal specifies CCMP/AES.
  91. 91What does RADIUS stand for?Remote Authentication Dial-In User Service
    maintains a user database or proxies to an external database like an LDAP database
  92. 92What is EAP?Extensible Authentication Protocol
    (many different flavors)
  93. 93What is LEAP?Cisco's version or EAP
    Lightweight Extensible Authentication Protocol
  94. 94What is PEAP?Protected Extensible Authentication Protocol
  95. 95How many steps are there to an EAP authentication?13
  96. 96What are the steps of an EAP authentication?Client associates to AP
    EAPOL-start sent to AP
    AP requests client ID
    Client responds with ID
    AP asks RADIUS for access
    RADIUS Challenges AP
    AP sends challenge to Client
    Client reponds to challenge
    AP sends client's response to RADIUS
    RADIUS sends accept to AP
    AP sends EAP success to Client
    4-way handshake between client & AP
    Controlled ports opened
  97. 97What is Dynamic Encryption Key Generation?a byproduct of 802.1x/EAP
    During the authentication process, AS and supplicant supply "seeding materials" to each other to help dynamically generate keys
  98. 98If someone is using WPA or WPA2 and don't have a RADIUS server, what can be used for authentication?PreShared Keys
    PSK
  99. 99How are CCMP keys generated?Dynamically during the 4 way handshake
  100. 100What is RBACRole Based Access Control
    estricting system access to
    authorized users. Many of the WLAN vendors provide RBAC capabilities. The three main components of an RBAC approach are users, roles, and permissions.
  101. 101What is the concept of interface security?If an interface isn't being used, it should be disabled.
  102. 102What is the most common layer 3 vpn protocol?IPSec
  103. 103How does an SSL vpn differ from a layer 3 vpn?Unlike an IPsec VPN, an SSL VPN does not require the installation
    and confi guration of client software on the end user’s computer. A user connects to a Secure Sockets Layer (SSL) VPN server via a web browser. The traffic between the web browser and the SSL VPN server is encrypted with the SSL protocol or Transport Layer Security (TLS). TLS and SSL encrypt data connections above the Transport layer
  104. 104What is client isolation?A feature to prevent P2P attacks between clients on a wireless network
  105. 105What kind of attack is undiscoverable by WIDS?Packet sniffing. Doesn't leave a trace because it's passive
  106. 106What is WPA/WPA2-Personal vulnerable to?offline brute-force dictionary attack to guess the PSK
  107. 107What is an overlay WIDS?Extra APs deployed to act simply as sensors to detect intrusion
  108. 108What is an integrated WIDS?(most common)
    NMS functions as an WIDS. Existing APs act as part time sensors
  109. 109What should you cover during customer interview for a site survey?What applications/purpose will wifi be used for?
    Who will be using wifi? Capacity/performance needs?
    What types of devices?
  110. 110What is a good saturation point for wifi devices using data?35-50 clients per AP
  111. 111what are 5 deliverables when performing a site survey?Purpose Statement
    Spectrum Analysis
    RF Coverage Analysis
    Hardware Placement and Configuration
    Capacity and Performance Analysis
  112. 112What is the most important issue when designing 802.11 for government?Security
  113. 113What is the most important issue when designing 802.11 for education?capacity
  114. 114What is the most important issue when designing 802.11 for healthcare?interference from other devices
  115. 115What is the most important issue when designing 802.11 for retail?2.4GHz interference
  116. 116What is the job of the spectrum analyzer?to detect possible interference
  117. 117Why are laptop NICs not good spectrum analyzers?They can't see raw RF, only encoded frames
  118. 118What are potential sources of interference in the 5GHz bands?Radar
    5GHz cordless phones
    Perimeter sensors
    Digital satellites
    nearby 5GHz networks
  119. 119What is a common mistake when performing a survey?Leaving the test AP at full power
  120. 120How do you figure out where to place the first test AP during a survey?Start in the corner of the building, place AP at desired power level, walk until signal hits -70dBM. Place first AP here.
  121. 121How do you figure out where to place 2nd AP?After placing first AP, walk parallel to the wall until signal drops to -70dBm
  122. 122How close must an AP be to an IDF?Within 100 Meters because of cable attenuation
  123. 123What are the two major types of coverage analysis?manual and predictive
    Manual is walking around with a test AP
    Predictive is loading up a floor plan and adding in building materials and AP power
  124. 124What is DRF and RRM?Dynamic RF
    radio resource management dynamically adjusts AP power and cell sized based on environmental conditions
  125. 125What needs to be done after a wireless network is installed?Network validation, a test to see that the network is performing as planned
  126. 126What is amendment standardized PoE?802.3af-2003
  127. 127what PoE standard sends power on the data pairs and which standard sends power on the unused pairs?data pairs - Alternative A
    unused pairs - Alternative B
  128. 128How many Watts of power in original 802.3af?15.4
  129. 129What 802.3 amendment increased the PoE Wattage from 15.4W to x?802.3at-2009
    25.5Watts total
  130. 130What is PSE and PD in relation to talking about PoE?Power Sourcing Equipment (send the power)
    Powered Device (gets da power)
  131. 131What is a common example of an endpoint PSE?A PoE capable switch
  132. 132How much power does a multi-radio AP need?Around 20Watts
  133. 133What new technology did 802.11n introduce?MIMO
  134. 134What is DSP?Digital Signal Processing
    802.11n and higher APs use it to sort out multipath signals
  135. 135What is STBC and CSD?Space-time block coding (STBC) and cyclic shift diversity (CSD) are
    transmit diversity techniques where the same transmit data is sent out of multiple antennas.
    STBC communication is possible only between 802.11n devices.
  136. 136What is a radio chain?a single radio and all of its supporting architecture, including mixers, amplifiers, and analog/digital converters.
  137. 137What is Spatial Multiplexing? (SM)MIMO radios will transmit multiple signals (data streams, or spatial streams) that will take different paths and create spatial diversity (helps MIMO)
  138. 138What do the numbers like 3x3x3 mean at the end of an AP?Tx:Rx:S
    transmit:receive:spatial streams
    3x3x3 = 3 transmit radio chains, 3 receive radio chains, 3 spatial streams
  139. 139What is MRC?maximal radio combining
    receiver diversity technique where multiple received signals are combined to raise SNR
  140. 140What is Space-Time Block Coding (STBC)?a method where the same information is transmitted on two or more antennas. It is a type of transmit diversity.
  141. 141Cyclic Shift Diversity (CSD)Cyclic shift diversity (CSD) is another transmit diversity technique specifi ed in the 802.11n standard. Unlike STBC, a signal from a transmitter that uses CSD can be received by legacy 802.11g and 802.11a devices
  142. 142What is Transmit Beamforming (TxBF) ?uses phase adjustments among multiple antennas to focus RF at a given point
  143. 143How does an AP know how to shape TxBF?Sounding frames sent to client to gather location information
  144. 144What size channels does 802.11n support?20Mhz and 40Mhz bonded
  145. 145What is Modulation and Coding Scheme (MCS) index?The MCS index value list gives every combination of "number of spatial streams + modulation type + coding rate" that is possible
  146. 146What is the main purpose of the preamble in a PPDU?to synchronize transmissions at the Physical layer
    between two 802.11 radio
  147. 147how does 802.11n make enhancements to the MAC sublayer?Frame aggregation to cut down on medium contention
  148. 148What is an A-MSDU802.11n - aggregated MAC Service Data Unit
    A-MSDU aggregation would receive multiple 802.3 frames, remove the 802.3 headers and trailers, and then wrap the multiple MSDU payloads into a single 802.11 frame for transmission
  149. 149What is an A-MPDUAggregate MAC Protocol Data Unit
    (A-MPDU).
    The individual MPDUs within an A-MPDU must all have the same receiver address.
    Also, the data payload of each MPDU is encrypted separately using the CCMP cipher. Much like MSDU aggregation, individual MPDUs must all be of the same 802.11e QoS access category
  150. 150What are the HT protection modes?Mode 0—Greenfield (No Protection) Mode
    Mode 1—HT Nonmember Protection Mode
    Mode 2—HT 20 MHz Protection Mode
    Mode 3—Non-HT Mixed Mode
  151. 151What is HT Protection Mode 0—Greenfield (No Protection) ModeThis mode is referred to as Greenfield
    because only HT radios are in use. All the HT client stations must also have the sameoperational capabilities. If the HT basic service set is a 20 MHz BSS, all the stations must be 20 MHz capable. If the HT basic service set is a 20/40 MHz BSS, all the stations must be 20/40 capable. If these conditions are met, there is no need for protection.
  152. 152What is HT Protection Mode 1 HT Nonmember Protection ModeIn this mode, all the stations in the BSS must be HT stations. Protection mechanisms kick in when a non-HT client station or non-HT access point is heard that is not a member of the BSS. For example, an HT AP and stations
    may be transmitting on a 40 MHz HT channel. A non-HT 802.11a access point or clientstation is detected to be transmitting in a 20 MHz space that interferes with either the primary or secondary channel of the 40 MHz HT channel.
  153. 153What is HT Protection Mode 2 HT 20 MHz Protection ModeIn this mode, all the stations in the BSS must be HT stations and are associated to a 20/40 MHz access point. If a 20 MHz–only HT station
    associates to the 20/40 MHz AP, protection must be used. In other words, the 20/40-capable HT stations must use protection when transmitting on a 40 MHz channel in order to prevent the 20 MHz–only HT stations from transmitting at the same time.
  154. 154What is HT Protection Mode 3 Non-HT Mixed ModeThis protection mode is used when one or more non-HT stations are associated to the HT access point. The HT basic service set can be either 20 MHz or 20/40 MHz capable. If any 802.11a/b/g radios associate to the BSS, protection will be used. Mode 3 will probably be the most commonly used protection mode because most basic service
    sets will most likely have legacy 802.11a/b/g devices as members.
  155. 155VHT is introduced in what amendment?802.11ac-2013
  156. 156In what bands does 802.11ac operate in?only 5Ghz U-NII bands
  157. 157how many modulation coding schemes does 802.11ac support?10
    down from 77 with 802.11n
  158. 158what size channels does 802.11ac support?20, 40, 80, and 160 MHz Channels
  159. 159what is dynamic bandwidth operation802.11ac feature, AP can choose channel width on a per frame basis (can hop around if one channel is busy)
  160. 160What are the two primary modulation methods used in 802.11 networksPhase Shift Keying (PSK)
    quadrature amplitude modulation (QAM)
  161. 161What is the highest data rate supported by QPSK?21.7Mbps
  162. 162What is the highest data rate supported by 16 QAM43.3Mbps
  163. 163What is the highest data rate supported by 64 QAM72.2Mbps
  164. 164What is the highest data rate supported by 256 QAM96.3Mbps
  165. 165What does an 802.11ac AP transmit at the start of a MU-MIMO beamforming process?Null data packets (NDP)
  166. 166What is a Block Acknowledgment Request (BAR)?An ACK request for the previously sent out block of aggregated frames
  167. 167What kind of backhaul is needed to support 802.11ac?gigabit ethernet
  168. 168What is NACNetwork access control (NAC) evaluates the capability or state of a computer to determine the potential risk of the computer on the network and to determine the level of access to
    allow.
  169. 169Where is Complimentary Code Keying (CCK) used?5.5 and 11 Mbps with HR/DSSS, which is supported by ERP-OFDM (802.11g) and HT (802.11n) devices operating in the 2.4 GHz frequency band.
  170. 170What kind of coding method is used at 1 and 2 Mbps?Baker
  171. 171Is data modulated and then encoded or encoded and then modulated to be sent out over RF?encoded and then modulated
  172. 172802.11a came out with what PHY standard?OFDM
  173. 173802.11b came out with what PHY standard?HR-DSSS
  174. 174802.11g came out with what PHY standardERP
  175. 175—

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CWNA Networking (CWNA) Flashcards on CWNA flashcards deck 2, created by Dustin Sanders on 16/11/2016.
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