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CCNA > Wireless Architectures > Flashcards

Wireless Architectures Flashcards

1
Q

T/F: Some fields of the 802.11 frame header might not be present, depending on the message

A

T

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2
Q

What is the Frame Control field in the 802.11 header for?

A

Providing message information such as message type and subtype

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3
Q

What is the Duration/ID field in the 802.11 header for?

A

Depending on the message, can indicate:
- Time channel will be dedicated for transmission of the frame
- Identifier for the association between AP and device

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4
Q

What are the Address fields in the 802.11 header for?

A
  • Destination Address (DA): final recipient of frame
  • Source Address (SA): original sender of frame
  • Receiver Address (RA): immediate recipient of the frame
  • Transmitter Address (TA): immediate sender of the frame
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5
Q

What is the Sequence Control field in the 802.11 header for?

A

Used to reassemble fragments and eliminate duplicate frames

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6
Q

What is the QoS Control field in the 802.11 header for?

A

QoS

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7
Q

What is the HT Control field in the 802.11 header for?

A

Enable High Throughput (HT) operations

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8
Q

The field after the encapsulated packet in an 802.11 frame is:

A

FCS, same as the ethernet frame

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9
Q

The Frame Check Sequence field in the 802.11 header is for:

A

Same as Ethernet frames, used for error checking

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10
Q

What are the three 802.11 connection states?

A
  • Not authenticated, not associated
  • Authenticated, not associated
  • Authenticated, associated

Client must be authenticated and associated with the AP to send traffic through it

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11
Q

What are the two ways a station can scan for a BSS?

A
  • Active Scanning: station sends probe requests and listens for probe response from AP
  • Passive Scanning: station listens for beacon messages from AP
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12
Q

T/F: Beacon messages are sent periodically by APs to advertise the BSS

A

T

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13
Q

T/F: Beacon messages are sent in response to probe requests sent by stations

A

F

Beacon messages are sent periodically

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14
Q

What are the three 802.11 message types?

A
  • Management
  • Control
  • Data
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15
Q

What is the 802.11 management message type used for?

A

Managing the BSS, including facilitating client discovery / connections

  • Beacon messages
  • Probe request, probe response
  • Authentication
  • Association request, association response
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16
Q

What is the 802.11 control message type used for?

A

Controlling access to the medium (RF). Assist with delivery of management and data frames

  • RTS (Request to send)
  • CTS (Clear to send)
  • ACK
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17
Q

What is the 802.11 data message type used for?

A

Sending actual data packets

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18
Q

In active scanning, a client sends ____ messages, and the AP response with _____ messaged

A

Probe request, probe response

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19
Q

After the discovery process is complete, the station sends ______ messages to the AP, and the AP replies with _____ messages

A

Authentication request, authentication response

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20
Q

After the authentication process is complete, the station sends _____ messages to the AP, and the AP replies with _____ messages

A

Association request, association response

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21
Q

Explain the difference between active scanning and passive scanning

A

Active scanning: The station sends a probe request message to the AP to initiate the connection process

Passive scanning: The station listens for beacon messages from the AP before initiating the connection process

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22
Q

What are the three main wireless AP deployment methods

A
  • Autonomous
  • Lightweight
  • Cloud-based
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23
Q

What is an Autonomous AP?

A

Self contained system that doesn’t rely on a wireless LAN controller. Must be manually configured per AP

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24
Q

T/F: Autonomous APs aren’t viable in larger networks

A

T

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25
Q

What is a Lightweight AP?

A

An AP that’s responsible for real time operations (Tx/Rx traffic, encrypt/decrypt, beacons/probes, etc), but other functions are carried out by a WLC. APs are also centrally managed by a WLC

AKA split-MAC architecture

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26
Q

How is an attacker prevented from using an unauthorized lightweight AP to join the WLAN?

A

X.509 standard certificates are used. The WLC and the APs authenticate each other using the certificates installed on each device.

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27
Q

What protocol is used to communicate between the WLC and the lightweight APs?

A

CAPWAP

Control And Provisioning of Wireless Access Points

28
Q

What protocol and port does the CAPWAP control tunnel use?

A

UDP 5246

29
Q

What protocol and port does the CAPWAP data tunnel use?

A

UDP 5247

30
Q

T/F: All traffic from wireless clients is sent through the CAPWAP data tunnel to the WLC, it doesn’t go directly to the wired network

A

T

31
Q

Explain how data travels from a client on the WLAN to a client on the LAN in the CAPWAP protocol

A

Data packets go through the CAPWAP data tunnel to the WLC, then from the WLC to the wired network

32
Q

What is the CAPWAP control tunnel used for?

A

Configuring APs, controlling and managing wireless operations.

33
Q

T/F: Even if a client is sending traffic to a client associated with the same lightweight AP, the traffic must first pass through the WLC first

A

T

All traffic must go to the WLC first via the CAPWAP data tunnel

34
Q

T/F: If a client is sending traffic to a client associated with the same AP, the traffic can go directly to the client to conserve wired network bandwidth

A

F

All traffic must go to the WLC first via the CAPWAP data tunnel

35
Q

T/F: Traffic in the CAPWAP control tunnel is encrypted by default

A

T

36
Q

T/F: Traffic in the CAPWAP data tunnel is encrypted by default

A

F

Traffic in the data tunnel isn’t encrypted by default, but can be configured to be encrypted with DTLS (Datagram Transport Layer Security)

37
Q

T/F: Since all traffic from wireless clients is tunneled to the WLC with CAPWAP, lightweight APs connect to switch access ports, not trunk ports

A

T

38
Q

T/F: Lightweight APs connect to switch trunk ports, since the traffic is tunneled to the WLC with CAPWAP

A

F

Lightweight APs send all traffic to the WLC with CAPWAP tunnels, so switch access ports are used

39
Q

T/F: In a split-MAC wireless architecture, a trunk is needed to connect the WLC to the wired network

A

T

Traffic is separated into VLANs by the WLC in a split-MAC architecture, not the APs

40
Q

T/F: In a split-MAC wireless architecture, a trunk is needed to connect both the WLC and the APs to the wired network

A

F

In a split-MAC architecture, the APs are connected via access ports, and the WLC is connected via a trunk port

41
Q

What are some benefits to using split-MAC architecture?

A
  • Scalability
  • Dynamic channel assignment
  • Transmit power optimization
  • Self-healing wireless coverage
  • Seamless roaming
  • Centralized security and QoS management
42
Q

What are the lightweight AP operational modes? (8)

A
  • Local
  • FlexConnect
  • Sniffer
  • Monitor
  • Rogue Detector
  • Spectrum Expert Connect
  • Bridge/Mesh
  • Flex Plus Bridge
43
Q

Explain the lightweight AP local operational mode

A

Default mode, AP offers one or more BSSs for clients to associate with

44
Q

Explain the lightweight AP FlexConnect operational mode

A

Similar to local mode, but allows the AP to locally switch traffic between wired and wireless networks if the AP loses its CAPWAP tunnel to the WLC

45
Q

Explain the lightweight AP sniffer operational mode

A

AP doesn’t offer a BSS for clients. Captures 802.11 frames and sends them to a device running software like Wireshark, etc.

46
Q

Explain the lightweight AP monitor operational mode

A

AP doesn’t offer a BSS for clients. Receives 802.11 frames and looks for rogue devices. If a client is found to be a rogue device, the AP can send de-authentication messages to disassociate the rogue device from the AP

47
Q

Explain the lightweight AP rogue detector operational mode

A

AP doesn’t use radio. Listens to wired network traffic only, but receives list of suspected rogue clients from the WLC. Listens to ARP messages on the wired network and compares to information from WLC to detect rogue devices.

48
Q

Explain the lightweight AP SE connect operational mode

A

AP doesn’t offer a BSS. Dedicated to RF spectrum analysis on all channels.

49
Q

Explain the lightweight AP bridge/mesh operational mode

A

AP can be a dedicated bridge between sites, or be used to create a mesh between APs

50
Q

Explain the lightweight AP Flex Plus Bridge operational mode

A

Adds FlexConnect functionality to the Bridge/Mesh mode. Allows APs to locally forward traffic even if connectivity to the WLC is lost

51
Q

What is a cloud-based AP?

A

Architecture in between autonomous AP and split-MAC architecture: Autonomous APs that are centrally managed in the cloud.

Only management traffic is sent to the cloud, data traffic stays on-prem

52
Q

T/F: With cloud-based APs, management traffic stays on-prem, but data traffic is sent to the cloud

A

F

The opposite is true

53
Q

T/F: With cloud-based APs, only management traffic is sent to the cloud, data traffic stays on-prem

A

T

54
Q

Cisco’s cloud based AP solution is:

A

Cisco Meraki

55
Q

What are the four main WLC deployment models in a split-MAC architecture?

A
  • Unified WLC
  • Cloud-based WLC
  • Embedded WLC
  • Cisco Mobility Express WLC
56
Q

Explain a unified WLC deployment

A

WLC is a hardware appliance in a central location of the network. Supports about 6000 APs, good for large enterprise

57
Q

Explain a cloud-based WLC deployment

A

The WLC is a VM running on a server, usually in a private cloud in a data center. not the same as the cloud-based AP architecture, i.e. Meraki. Supports about 3000 APs

58
Q

Explain an embedded WLC deployment

A

The WLC is integrated within a switch. Supports around 200 APs per switch WLC.

59
Q

Explain a mobility express WLC deployment

A

The WLC is integrated within an AP. Supports about 100 APs, good for a small branch office

60
Q

What kind of message is an 802.11 probe request?

a) Data
b) Control
c) Management
d) Beacon

A

c) Management

61
Q

Which of the following AP types are centrally managed? (Pick many)

a) Autonomous
b) WGB
c) Lightweight
d) Cloud-based

A

c) Lightweight
d) Cloud-based

62
Q

Which of the following AP types uses the CAPWAP protocol?

a) Autonomous
b) WGB
c) Lightweight
d) Cloud-based

A

c) Lightweight

63
Q

Which of the following lightweight AP modes offer a BSS for clients? (pick many)

a) Local
b) Sniffer
c) FlexConnect
d) Rogue Detector

A

a) Local
c) FlexConnect

64
Q

Which of the following WLC deployments supports the greatest number of APs?

a) Embedded
b) Cloud-based
c) Mobility Express
d) Unified

A

d) Unified

65
Q

Order the following 802.11 MAC frame header fields in the correct order
- ADD1
- ADD2
- ADD3
- ADD4
- DATA
- DUR
- FC
- FCS
- SEQ

A

FC
DUR
ADD1
ADD2
ADD3
SEQ
ADD4
DATA
FCS

66
Q
A

CCNA (38 decks)

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