Wireless Standards And Protocols Test For Beginners!
- 1.
As XYZ Company’s wireless specialist, you have been asked to troubleshoot some unexpected frame patterns in a wireless protocol capture. Your peers explain that the network’s beacon frames are inconsistent. That is, the BSSID is the same for all beacons, but the source address varies between three different addresses. What network configuration would cause this beacon frame behavior?
- A.
A single AP supports multiple BSSs with different SSIDs
- B.
The beacons are from an IBSS instead of a BSS
- C.
A virtual cell single channel network has been implemente
- D.
Three APs still share the same default configuration.
Correct Answer
B. The beacons are from an IBSS instead of a BSSExplanation
The inconsistent beacon frames with the same BSSID but different source addresses indicate that the beacons are from an Independent Basic Service Set (IBSS) instead of a Basic Service Set (BSS). In an IBSS, also known as an ad hoc network, devices communicate directly with each other without the need for an access point. Each device acts as a peer and can take turns transmitting beacons with its own source address. This behavior is different from a BSS, where the access point is responsible for transmitting the beacons with a consistent source address.Rate this question:
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- 2.
When compared with legacy Power Save mode, how does VHT TXOP power save improve battery life for devices on a WLAN?
- A.
VHT TXOP power save allows stations to enter sleep mode and legacy Power Save does not.
- B.
Legacy Power Save mode was removed in the 802.11ac amendment
- C.
VHT TXOP power save uses the partial AID in the preamble to allow clients to identify frames targeted for them.
- D.
VHT TXOP power save allows the WLAN transceiver to disable more components when in a low power state.
Correct Answer
C. VHT TXOP power save uses the partial AID in the preamble to allow clients to identify frames targeted for them.Explanation
VHT TXOP power save improves battery life for devices on a WLAN by using the partial AID in the preamble to allow clients to identify frames targeted for them. This means that devices can selectively wake up and process only the frames that are intended for them, reducing the overall power consumption. By efficiently managing the power usage, VHT TXOP power save helps to extend the battery life of devices on a WLAN.Rate this question:
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- 3.
As defined in the 802.11 specification, legacy Power Save requires an inefficient back-and-forth frame exchange process. Due to this inefficiency, many WLAN device implementations use a variation of 802.11 Power Save to accomplish the same function. What non-standard power save behavior is used by most Wi-Fi devices in actual legacy Power Save implementations?
- A.
Client devices ignore the TIM field and automatically send PS-Poll frames after every beacon
- B.
Clients send null data frames to the AP and switch the power management bit from 1 to 0 to receive queued data.
- C.
After each beacon, the AP attempts to empty its frame buffer by sending Wake-on-WLAN frames to wake each dozing client
- D.
Request-to-Send and Clear-to-Send frame exchanges are used to trigger the delivery of buffered data.
- E.
The Beacon interval is changed from the default 100 time units to 10 or less time units.
- F.
Stations send a CTS-to-self frame to the AP with a very long duration period so they can receive all of their buffered data at once.
Correct Answer
B. Clients send null data frames to the AP and switch the power management bit from 1 to 0 to receive queued data.Explanation
In most Wi-Fi devices, the non-standard power save behavior used in actual legacy Power Save implementations is that clients send null data frames to the AP and switch the power management bit from 1 to 0 to receive queued data. This allows the clients to conserve power by entering a sleep mode while still being able to receive any data that is waiting for them. By sending null data frames and changing the power management bit, the clients can effectively control when they want to receive the queued data from the AP.Rate this question:
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- 4.
What term correctly completes the following sentence? In an IEEE 802.11 frame, the IP packet is considered by the MAC layer to be a(n) _________.
- A.
MAC Protocol Data Unit (MPDU)
- B.
MAC Service Data Unit (MSDU)
- C.
IP datagram
- D.
PLCP Service Data Unit (PSDU)
- E.
PLCP Protocol Data Unit (PPDU)
Correct Answer
B. MAC Service Data Unit (MSDU)Explanation
In an IEEE 802.11 frame, the IP packet is considered by the MAC layer to be a(n) MAC Service Data Unit (MSDU). This term refers to the data unit that is passed from the higher layer (network layer) to the MAC layer for transmission over the wireless medium. The MSDU includes the IP packet along with any necessary headers or trailers added by the MAC layer.Rate this question:
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- 5.
What term correctly completes the following sentence? 802.11a/b/g used a mandatory 800ns guard interval. 802.11n introduced an optional short 400ns guard interval. Guard intervals (GI) are necessary in OFDM to reduce the likelihood of interference between two consecutive ____________.
- A.
Frames
- B.
Packets
- C.
Symbols
- D.
Bytes
- E.
Bits
Correct Answer
C. SymbolsExplanation
Guard intervals (GI) are necessary in OFDM to reduce the likelihood of interference between two consecutive symbols. In the context of the given question, 802.11a/b/g and 802.11n are wireless communication standards that use OFDM (Orthogonal Frequency Division Multiplexing) modulation. The guard interval is a period of time inserted between symbols to mitigate the effects of multipath interference. Therefore, the correct term to complete the sentence is "Symbols".Rate this question:
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- 6.
Prior to association, what parameter can 802.11 client devices measure and use to select the optimal access point for association?
- A.
Proximity to potential access points
- B.
Signal strength of access point beacons received
- C.
Retry rate of probe request and response frames
- D.
Average round trip time to reach the Internet DNS server
- E.
Average round trip time to reach the IP router
Correct Answer
B. Signal strength of access point beacons receivedExplanation
802.11 client devices can measure and use the signal strength of access point beacons received to select the optimal access point for association. This is because the signal strength indicates the quality of the connection between the client device and the access point. A stronger signal strength suggests a better connection and therefore a more optimal access point for association.Rate this question:
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- 7.
In an infrastructure Basic Service Set (BSS), how does the passive scanning process occur?
- A.
Client stations broadcast Probe Request frames on all supported channels in the regulatory domain. Nearby access points respond with Probe Response frames. Client stations record information in the Probe Response frames for use in the association process.
- B.
Client stations broadcast Probe Request frames on the single channel for which they are programmed. Nearby access points respond on that channel with Probe Response frames. Client stations record information found in the Probe Response frames for use in the association process
- C.
Access points broadcast Beacons on a single channel for which they are programmed. Nearby client stations listen for Beacon frames and record information found in the Beacons for use in the association process.
- D.
Access points broadcast Beacons on all channels of each radio within the regulatory domain. Nearby client stations record information found in the Beacons for use in the association process.
Correct Answer
C. Access points broadcast Beacons on a single channel for which they are programmed. Nearby client stations listen for Beacon frames and record information found in the Beacons for use in the association process.Explanation
In an infrastructure Basic Service Set (BSS), the passive scanning process occurs when access points broadcast Beacon frames on a single channel for which they are programmed. Nearby client stations listen for these Beacon frames and record the information found in them. This information is then used by the client stations in the association process, allowing them to connect to the appropriate access point in the BSS.Rate this question:
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- 8.
During the discovery and connectivity process, client and AP stations exchange information about their supported data rates. After the association, how do client and AP stations select the supported data rate that will be used to send an 802.11 data frame?
- A.
During the association, the client and AP agree to use the same transmit rate, but either station can request a change at any time after the association.
- B.
The client and AP may use different transmit rates, but the AP determines the data rate that will CWNA CWNA-106 Exam "Pass Any Exam. Any Time." - www.actualtests.com 24 be used by each client station in the BSS
- C.
The client and AP each choose the optimal data rate to use independently of one another, based on their own measurements related to the RF link.
- D.
The client and AP may use a different transmit rates, but the transmit rate is determined by the peer station, based on the peer’s experience of the RF link.
- E.
The client and AP may use a different transmit rates, but the transmit rate is determined by the peer station, based on the peer’s experience of the RF link.
Correct Answer
C. The client and AP each choose the optimal data rate to use independently of one another, based on their own measurements related to the RF link.Explanation
During the association process, both the client and AP stations independently select the optimal data rate to use for sending 802.11 data frames. This selection is based on their own measurements and observations of the RF link. The client and AP do not rely on each other to determine the data rate. They agree to use the same transmit rate initially, but either station can request a change at any time after the association.Rate this question:
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- 9.
As a station moves away from the access point to which it is associated, it changes its data rate from 600 Mbps to 540 Mbps and then to 450 Mbps. What IEEE 802.11 term is used to describe this functionality?
- A.
Multirate Control
- B.
Modulation and Coding Selection
- C.
Rate Set Selectivity
- D.
Dynamic Rate Switching
- E.
Adaptive Rate Management
Correct Answer
D. Dynamic Rate SwitchingExplanation
Dynamic Rate Switching is the term used to describe the functionality where a station changes its data rate as it moves away from the associated access point. This feature allows the station to maintain a stable connection by adjusting the data rate based on the signal strength and quality.Rate this question:
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- 10.
What statement about the IEEE 802.11e QoS facility is true?
- A.
When the Voice queue has frames awaiting transmission, no data will be transmitted from the Best Effort queue.
- B.
To improve efficiency, Block Acknowledgments are required for Voice and Video WMM queues
- C.
802.11 QoS is achieved by giving high priority queues a statistical advantage at winning contention.
- D.
Four 802.1p user priorities are mapped to eight 802.11 transmit queues.
- E.
802.11 control frames are assigned to the 802.11 EF priority queue.
Correct Answer
C. 802.11 QoS is achieved by giving high priority queues a statistical advantage at winning contention.Explanation
The statement that is true about the IEEE 802.11e QoS facility is that 802.11 QoS is achieved by giving high priority queues a statistical advantage at winning contention. This means that the high priority queues have a higher chance of accessing the wireless medium and transmitting their frames, resulting in improved quality of service for those queues.Rate this question:
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- 11.
What distinguishes an independent basic service set (IBSS) from an infrastructure basic service set (BSS)?
- A.
An IBSS does not require beacon frames, but a BSS does.
- B.
An IBSS does not support 802.11 authentication or association, but a BSS does
- C.
An IBSS does not have a distribution system (DS), but a BSS does.
- D.
An IBSS does not support any 802.11ac enhancements, but a BSS does.
Correct Answer
C. An IBSS does not have a distribution system (DS), but a BSS does.Explanation
An independent basic service set (IBSS) is a type of wireless network where devices communicate directly with each other without the need for a centralized access point. In an IBSS, there is no distribution system (DS) which refers to the infrastructure that connects multiple access points together to form a larger network. On the other hand, an infrastructure basic service set (BSS) relies on a distribution system (DS) to connect multiple access points and create a larger network. Therefore, the distinguishing factor between an IBSS and a BSS is that an IBSS does not have a distribution system (DS), while a BSS does.Rate this question:
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- 12.
What statements about the SSID are true? (Choose 2)
- A.
When configuring a new network, creating an SSID is optional.
- B.
The SSID must be included in an association request frame.
- C.
The SSID is an alphanumeric value assigned to device manufacturers by the IEEE.
- D.
The SSID is an alphanumeric value with a maximum length of 32 octets.
- E.
The SSID is a security session identifier used in RSNs.
Correct Answer(s)
B. The SSID must be included in an association request frame.
D. The SSID is an alpHanumeric value with a maximum length of 32 octets.Explanation
The SSID must be included in an association request frame because it is used to identify the network that a device wants to connect to. The SSID is an alphanumeric value with a maximum length of 32 octets, which means it can contain letters, numbers, and special characters and cannot exceed 32 characters in length. This limit is set to ensure compatibility and efficient communication between devices.Rate this question:
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- 13.
In an enterprise WLAN, what condition will prevent a dual-band VHT/HT client device from performing a fast and seamless transition (i.e. latency-sensitive applications are not disrupted) between two access points that are managed by the same WLAN controller?
- A.
The current AP is using channel 1 and the new AP is using channel 40.
- B.
The current AP supports only HT and the new AP is VHT capable.
- C.
The SSID of the current AP does not match the SSID of the new AP.
- D.
The access points are hiding the SSID in Beacons and Probe Response frames.
Correct Answer
C. The SSID of the current AP does not match the SSID of the new AP.Explanation
If the SSID of the current AP does not match the SSID of the new AP, it will prevent a dual-band VHT/HT client device from performing a fast and seamless transition between the two access points. The SSID is the unique identifier of the wireless network, and if it does not match, the client device will not be able to connect to the new AP smoothly. This can cause disruptions in latency-sensitive applications as the device may experience a delay or loss of connection during the transition.Rate this question:
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- 14.
When a client moves to a new BSS within an ESS, what steps are part of the 802.11 reassociation process? (Choose 2)
- A.
The current access point informs the IP gateway of the reassociation
- B.
The current access point triggers the client’s reassociation service.
- C.
The new access point transmits a Reassociation Response to the client station with a status value.
- D.
The client and new access point create unicast encryption keys.
- E.
The client station transmits a deauthentication frame to the current access point.
- F.
The client station transmits a Reassociation Request frame to its current access point.
Correct Answer(s)
C. The new access point transmits a Reassociation Response to the client station with a status value.
D. The client and new access point create unicast encryption keys.Explanation
When a client moves to a new BSS within an ESS, the 802.11 reassociation process involves the following steps:
1) The new access point transmits a Reassociation Response to the client station with a status value, indicating the success or failure of the reassociation.
2) The client and new access point create unicast encryption keys to establish a secure communication channel. These keys are used to encrypt and decrypt data between the client and the new access point.Rate this question:
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- 15.
A Wi-Fi Alliance interoperability certificate indicates that a device is a/b/g/n certified. It further indicates one transmit and receive spatial stream for both the 2.4 GHz and 5.0 GHz bands. It further indicates support for both WPA and WPA2 Enterprise and Personal. Finally, it indicates support for EAP-TLS, EAP-TTLS/MSCHAPv2, PEAPv0/EAP-MSCHAPv2 and PEAPv1/EAP-GTC. Which one of the following statements is false?
- A.
This client device supports both TKIP and CCMP cipher suites.
- B.
This client device supports protection mechanisms such as RTS/CTS and/or CTS-to-Self.
- C.
300 Mbps is the maximum supported data rate for this device.
- D.
This client device supports the ERP, OFDM, and HT physical layer specifications.
- E.
This client device supports X.509 certificates for EAP authentication.
Correct Answer
C. 300 Mbps is the maximum supported data rate for this device.Explanation
The given statement is false because the question states that the device is a/b/g/n certified, which means it supports up to 600 Mbps data rates for both the 2.4 GHz and 5.0 GHz bands. Therefore, the maximum supported data rate for this device is not 300 Mbps.Rate this question:
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- 16.
Which data rate is supported by 802.11g radios that is not supported by 802.11a radios?
- A.
9 Mbps
- B.
12 Mbps
- C.
11 Mbps
- D.
54 Mbps
- E.
65 Mbps
- F.
130 Mbps
Correct Answer
C. 11 MbpsExplanation
802.11g radios support a data rate of 11 Mbps, which is not supported by 802.11a radios. The 802.11a standard supports data rates of 6, 9, 12, 18, 24, 36, 48, and 54 Mbps, while the 802.11g standard supports data rates of 1, 2, 5.5, 6, 9, 11, 12, 18, 24, 36, 48, and 54 Mbps. Therefore, the correct answer is 11 Mbps.Rate this question:
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- 17.
Which of the following frequency ranges are specified for use by IEEE 802.11 radios? (Choose all that apply.)
- A.
902 - 928 MHz B
- B.
2.4000 – 2.4835 GHz
- C.
5.15 – 5.25 GHz
- D.
5.470 – 5.725 GHz
- E.
5.725 – 5.875 GHz
Correct Answer(s)
B. 2.4000 – 2.4835 GHz
C. 5.15 – 5.25 GHz
D. 5.470 – 5.725 GHz
E. 5.725 – 5.875 GHzExplanation
The frequency ranges specified for use by IEEE 802.11 radios are 2.4000 – 2.4835 GHz, 5.15 – 5.25 GHz, 5.470 – 5.725 GHz, and 5.725 – 5.875 GHz. These frequency ranges are commonly used for Wi-Fi communication and are regulated by the IEEE 802.11 standard.Rate this question:
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- 18.
The OSI model is a 7-layer model for understanding the functions of a communication system. What OSI sublayers are specifically addressed by the IEEE 802.11-2012 standard? (Choose 2)
- A.
PLCP
- B.
IP
- C.
MAC
- D.
. Transport
- E.
Network
- F.
. PPDU
Correct Answer(s)
A. PLCP
C. MACExplanation
The IEEE 802.11-2012 standard specifically addresses the PLCP (Physical Layer Convergence Protocol) and MAC (Media Access Control) sublayers of the OSI model. These sublayers are essential for the functioning of a communication system using the IEEE 802.11-2012 standard. The PLCP sublayer is responsible for providing a reliable physical connection between devices, while the MAC sublayer handles the access to the shared communication medium and manages the data transmission.Rate this question:
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- 19.
What features were introduced in the IEEE 802.11h amendment in order to uphold regulatory requirements for 5 GHz operation? (Choose 2) .
- A.
. Radio Resource Management (RRM)
- B.
. Phase Shift Keying (PSK)
- C.
Dynamic Frequency Selection (DFS)
- D.
. Transmit Power Control (TPC)
- E.
256-QAM
- F.
Distributed Coordination Function (DCF)
Correct Answer(s)
C. Dynamic Frequency Selection (DFS)
D. . Transmit Power Control (TPC)Explanation
The IEEE 802.11h amendment introduced Dynamic Frequency Selection (DFS) and Transmit Power Control (TPC) features in order to uphold regulatory requirements for 5 GHz operation. DFS allows devices to detect and avoid interference from radar systems by dynamically selecting and switching to available frequency channels. TPC enables devices to adjust their transmit power levels to comply with regulatory limits and avoid interference with other devices operating in the same frequency band. These features help ensure efficient and interference-free operation in the 5 GHz spectrum.Rate this question:
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- 20.
The IEEE 802.11a/n/ac physical layer technologies utilize the 5 GHz frequency band. What is true of the channels in this frequency spectrum?
- A.
14 channels are available worldwide
- B.
DFS may be required in some regulatory domains on some channels
- C.
Regulatory domains worldwide require DFS and TPC in all these channels.
- D.
11 channels are available worldwide.
- E.
802.11 channels are separated by 5 Mhz
Correct Answer
B. DFS may be required in some regulatory domains on some channelsExplanation
The correct answer is that DFS (Dynamic Frequency Selection) may be required in some regulatory domains on some channels. This means that in certain regions or countries, certain channels within the 5 GHz frequency band may require DFS to avoid interference with radar systems. DFS allows devices to detect radar signals and switch to a different channel if necessary. However, it is important to note that DFS is not required in all regulatory domains or on all channels, hence the use of "may be required" in the answer.Rate this question:
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- 21.
When a client station sends a broadcast probe request frame with a wildcard SSID, how do APs respond?
- A.
After waiting a SIFS, a designated AP sends an ACK, and then replies with a probe response.
- B.
For each probe request frame, only one AP may reply with a probe response
- C.
Each AP checks with the DHCP server to see if it can respond and then acts accordingly
- D.
Each AP responds in turn after preparing a probe response and winning contention
- E.
After waiting a SIFS, all APs reply at the same time with a probe response.
Correct Answer
D. Each AP responds in turn after preparing a probe response and winning contentionExplanation
When a client station sends a broadcast probe request frame with a wildcard SSID, each AP responds in turn after preparing a probe response and winning contention. This means that each AP will wait for its turn to respond, ensuring that there is no collision in the transmission. After waiting a SIFS (Short Interframe Space), the designated AP sends an ACK (Acknowledgement) to confirm the receipt of the probe request. Then, each AP prepares a probe response and checks if it has won contention, meaning it has the right to respond. Only one AP will be selected to send the probe response to the client station.Rate this question:
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- 22.
In an 802.11n 2.4 GHz BSS, what prevents each station from using the full network bandwidth (e.g. 130 Mbps) for user data throughput when multiple clients are actively exchanging data with the AP? (Choose 2)
- A.
. Radio receiver hardware cannot process data as quickly as it can be transmitted.
- B.
WLAN devices cannot detect collisions and must receive positive frame acknowledgment
- C.
. Half of the bandwidth is allocated to uplink traffic and half to downlink traffic
- D.
. APs do not have sufficient wired connection speeds to the LAN.
- E.
The DCF and EDCA coordination functions require backoff algorithms
Correct Answer(s)
B. WLAN devices cannot detect collisions and must receive positive frame acknowledgment
E. The DCF and EDCA coordination functions require backoff algorithmsExplanation
WLAN devices cannot detect collisions and must receive positive frame acknowledgment because collisions can occur when multiple devices attempt to transmit data at the same time, causing data loss and decreased network efficiency. The DCF and EDCA coordination functions require backoff algorithms to manage access to the shared medium and prevent collisions. These algorithms introduce a random delay before retransmitting data, allowing other devices to have a chance to transmit and reducing the likelihood of collisions.Rate this question:
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- 23.
What answers correctly complete the following sentence? ____________ and ____________ carrier sense functions are used to determine if the wireless medium is busy. (Choose 2)
- A.
Backoff
- B.
Pseudo-random
- C.
Virtual
- D.
Active
- E.
Vector
- F.
. Physical
- G.
Interframe
Correct Answer(s)
C. Virtual
F. . pHysicalExplanation
Virtual and Physical carrier sense functions are used to determine if the wireless medium is busy. Virtual carrier sense is a mechanism used in wireless networks to detect the presence of other devices on the network by listening to the medium. Physical carrier sense, on the other hand, involves sensing the actual physical properties of the medium, such as signal strength or energy levels, to determine if it is being used by another device. Both of these functions are important in ensuring that devices can access the wireless medium without causing interference or collisions.Rate this question:
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- 24.
The center frequency of channel 1 in the 2.4 GHz band is 2.412 GHz (2412 MHz). What is the center frequency of channel 4
- A.
2.427 GHz
- B.
2.422 GHz
- C.
2.437 GHz
- D.
2.417 GHz
- E.
2.413 GHz
Correct Answer
A. 2.427 GHzExplanation
The center frequency of channel 4 in the 2.4 GHz band is 2.427 GHz. This can be determined by adding 5 MHz to the center frequency of channel 1 (2.412 GHz), since each channel in the 2.4 GHz band is spaced 5 MHz apart.Rate this question:
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- 25.
What facts are true regarding controllers and APs in a Split MAC architecture? (Choose 2)
- A.
With 802.1X/EAP security, the AP acts as the supplicant and the controller acts as the authenticator
- B.
An IP tunnel is established between the AP and controller for AP management and control functions.
- C.
Using centralized data forwarding, APs never tag Ethernet frames with VLAN identifiers or 802.1p CoS.
- D.
Management and data frame types must be processed locally by the AP, while control frame types must be sent to the controller.
- E.
In a distributed data forwarding model, the AP handles frame encryption and decryption.
Correct Answer(s)
B. An IP tunnel is established between the AP and controller for AP management and control functions.
E. In a distributed data forwarding model, the AP handles frame encryption and decryption.Explanation
In a Split MAC architecture, an IP tunnel is established between the AP and controller for AP management and control functions. This allows the controller to manage and control the AP remotely. Additionally, in a distributed data forwarding model, the AP handles frame encryption and decryption. This means that the AP is responsible for securing the data frames by encrypting and decrypting them before transmitting them over the network.Rate this question:
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- 26.
In an 802.11 2.4 GHz system, what 22 MHz channels are considered non-overlapping? (Choose 2)
- A.
Channels 10 and 13
- B.
Channels 2 and 8
- C.
Channels 8 and 11
- D.
Channels 10 and 13
- E.
Channels 5 and 10
- F.
Channels 1 and 5
Correct Answer(s)
B. Channels 2 and 8
E. Channels 5 and 10Explanation
In an 802.11 2.4 GHz system, channels 2 and 8 are considered non-overlapping because they have a separation of 6 channels between them. Similarly, channels 5 and 10 are also non-overlapping as they have a separation of 5 channels between them. The non-overlapping channels are used to minimize interference between neighboring wireless networks operating on the same frequency band.Rate this question:
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- 27.
What are two channel modes specified by the 802.11n (High Throughput) pHY? (Choose 2)
- A.
40/80 MHz
- B.
. 20/40 MHz
- C.
160 MHz
- D.
22 MHz
- E.
80 MHz
- F.
20 MHz
Correct Answer(s)
B. . 20/40 MHz
F. 20 MHzExplanation
The 802.11n (High Throughput) PHY specifies two channel modes: 20/40 MHz and 20 MHz. These channel modes determine the width of the channel used for wireless communication. The 20/40 MHz mode allows for the use of both 20 MHz and 40 MHz channel widths, providing increased bandwidth and throughput. The 20 MHz mode, on the other hand, uses a narrower channel width, which may be preferred in certain situations where interference or congestion is a concern.Rate this question:
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- 28.
What factors will have the most significant impact on the amount of wireless bandwidth available to each station within a BSS? (Choose 2)
- A.
The power management settings in the access point’s beacons
- B.
The number of client stations associated to the BSS
- C.
The presence of co-located (10m away) access points on non-overlapping channels
- D.
The data rates at which nearby client stations are transmitting and receiving data
- E.
The layer 3 protocol used by each station to transmit data over the wireless link
Correct Answer(s)
B. The number of client stations associated to the BSS
D. The data rates at which nearby client stations are transmitting and receiving dataExplanation
The number of client stations associated to the BSS will have a significant impact on the amount of wireless bandwidth available to each station because as the number of stations increases, the available bandwidth will be divided among them, resulting in lower bandwidth for each station.
The data rates at which nearby client stations are transmitting and receiving data will also have a significant impact on the available bandwidth. If nearby stations are using high data rates, it can reduce the available bandwidth for other stations in the BSS.Rate this question:
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- 29.
What factors are likely to cause the greatest impact on the application layer throughput of an 802.11n client station in a 2.4 GHz HT BSS? (Choose 3)
- A.
Increasing or decreasing the number of spatial streams in use by the client station and AP
- B.
Increasing the beacon interval from 100 to 200 (TUs)
- C.
Use of WEP or TKIP for encryption instead of CCMP
- D.
RF interference from more than 10 nearby Bluetooth transmitters
- E.
Use of passphrase authentication instead of 802.1X/EAP authentication
Correct Answer(s)
A. Increasing or decreasing the number of spatial streams in use by the client station and AP
C. Use of WEP or TKIP for encryption instead of CCMP
D. RF interference from more than 10 nearby Bluetooth transmittersExplanation
Increasing or decreasing the number of spatial streams in use by the client station and AP can have a significant impact on the application layer throughput of an 802.11n client station. Spatial streams are a key feature of 802.11n that allow for multiple data streams to be transmitted simultaneously, increasing the overall throughput. By increasing or decreasing the number of spatial streams, the client station and AP can adjust the data transmission rate to optimize performance.
The use of WEP or TKIP for encryption instead of CCMP can also impact the application layer throughput. WEP and TKIP are older and less secure encryption methods, which can introduce additional overhead and reduce the overall throughput compared to the more efficient CCMP encryption.
RF interference from more than 10 nearby Bluetooth transmitters can also cause a significant impact on the application layer throughput. Bluetooth operates in the same frequency range as 2.4 GHz Wi-Fi, and the interference from multiple Bluetooth devices can degrade the Wi-Fi signal, leading to reduced throughput and performance.Rate this question:
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- 30.
In addition to throughput enhancements, what other improvements does a dual-band 802.11ac AP provide when compared with 802.11a/g APs? (Choose 2)
- A.
Improves service quality for real-time applications at greater distances
- B.
Introduces “fast transition” roaming protocols for VoWiFi phones
- C.
Increases in receive sensitivity enhance RTLS location accuracy
- D.
Better link reliability between 802.11a/b/g client devices and 802.11ac APs
- E.
Stronger security with more robust encryption modes.
Correct Answer(s)
A. Improves service quality for real-time applications at greater distances
D. Better link reliability between 802.11a/b/g client devices and 802.11ac APsExplanation
A dual-band 802.11ac AP provides improvements in service quality for real-time applications at greater distances. This means that users can experience better performance and reliability when using applications that require real-time data transmission, such as video streaming or online gaming, even when they are farther away from the access point. Additionally, a dual-band 802.11ac AP offers better link reliability between 802.11a/b/g client devices and the access point. This means that devices using older Wi-Fi standards can still maintain a strong and stable connection with the access point, ensuring a seamless user experience.Rate this question:
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- 31.
The IEEE 802.11-2012 standard requires VHT capable devices to be backward compatible with devices using which other 802.11 physical layer specifications (pHYs)? (Choose 2)
- A.
DSSS-OFDM
- B.
HT
- C.
HR/DSSS
- D.
OFDM
- E.
ERP-PBCC
Correct Answer(s)
B. HT
D. OFDMExplanation
The IEEE 802.11-2012 standard requires VHT capable devices to be backward compatible with devices using the HT and OFDM physical layer specifications. This means that VHT capable devices should be able to communicate with devices that use the HT and OFDM PHYs, ensuring compatibility and interoperability between different generations of devices. This requirement allows for a smooth transition and coexistence between older and newer devices in a wireless network.Rate this question:
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- 32.
Which IEEE 802.11 physical layer (pHY) specifications include support for and compatibility of both OFDM and HR/DSSS? (Choose 2)
- A.
VHT (802.11ac)
- B.
HT (802.11n)
- C.
CCK (802.11b)
- D.
HR/DSSS (802.11b)
- E.
OFDM (802.11a)
- F.
ERP (802.11g)
Correct Answer(s)
B. HT (802.11n)
F. ERP (802.11g)Explanation
The correct answer is HT (802.11n) and ERP (802.11g). These two IEEE 802.11 physical layer specifications include support for and compatibility of both OFDM and HR/DSSS. OFDM is a modulation scheme used in 802.11a and 802.11n, while HR/DSSS is used in 802.11b. HT (802.11n) supports both OFDM and HR/DSSS, making it compatible with both 802.11a and 802.11b. Similarly, ERP (802.11g) also supports both OFDM and HR/DSSS, making it compatible with both 802.11a and 802.11b.Rate this question:
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- 33.
As a consultant, you’ve been hired by XYZ Company to provide recommendations about client device selection, operation, and interoperability. What information should be considered to help them choose the right WLAN client devices?
- A.
802.11ac devices support the features of the VHT PHY only in the 5 GHz frequency band.
- B.
802.11n OFDM is more susceptible to high-power, narrowband interference than 802.11a
- C.
In order to earn Wi-Fi Alliance certification, 802.11n clients stations are required to support both 2.4 and 5 GHz frequencies
- D.
When HR/DSSS devices are present, VHT MCS rates are disabled for the entire BSS.
- E.
802.11ac is not backwardly compatible with 802.11n or 802.11a.
Correct Answer
A. 802.11ac devices support the features of the VHT pHY only in the 5 GHz frequency band.Explanation
The correct answer is that 802.11ac devices support the features of the VHT PHY only in the 5 GHz frequency band. This information is important for XYZ Company to consider when choosing the right WLAN client devices because it indicates that if they want to take advantage of the higher speeds and capabilities offered by the VHT PHY, they will need to ensure that their client devices are operating in the 5 GHz frequency band. This may influence their decision on which devices to select and how to configure their wireless network.Rate this question:
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- 34.
What statement is true concerning the use of Orthogonal Frequency Division Multiplexing (OFDM) in IEEE 802.11 WLANs?
- A.
With 802.11a OFDM, 16-QAM provides either 48 or 54 Mbps data rates, depending upon coding rates
- B.
802.11ac VHT-OFDM utilizes 256-QAM, which increases the data rate significantly over 64QAM available in HT-OFDM.
- C.
In 802.11a OFDM, fifty-six (56) subcarriers are used as parallel symbol transmission paths to carry data
- D.
802.11a/g/n OFDM includes several combinations of modulation and coding to achieve data rates from 1-600 Mbps
- E.
802.11a and 11n use six (6) “pilot” subcarriers as a reference for the receiver to detect frequency and phase shifts of the signal.
Correct Answer
B. 802.11ac VHT-OFDM utilizes 256-QAM, which increases the data rate significantly over 64QAM available in HT-OFDM.Explanation
802.11ac VHT-OFDM utilizes 256-QAM, which increases the data rate significantly over 64QAM available in HT-OFDM. This means that 802.11ac can transmit more data per symbol, resulting in higher data rates.Rate this question:
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- 35.
What statements accurately describe the RF cables and connectors that are used in an 802.11 WLAN system? (Choose 3)
- A.
75 and 125 ohms are the typical impedances of 802.11 WLAN connectors.
- B.
RF cables have upper and lower frequency range specifications.
- C.
Two RF connectors of the same type (e.g. SMA), manufactured by different companies, may vary in specifications. D. Every RF connector
- D.
Every RF connector causes insertion loss.
- E.
Large diameter RF cables cause greater loss than small diameter cables.
Correct Answer(s)
B. RF cables have upper and lower frequency range specifications.
C. Two RF connectors of the same type (e.g. SMA), manufactured by different companies, may vary in specifications. D. Every RF connector
D. Every RF connector causes insertion loss.Explanation
RF cables have upper and lower frequency range specifications, meaning that they can only transmit signals within a certain frequency range. Two RF connectors of the same type, but manufactured by different companies, may vary in specifications, which can affect their compatibility and performance. Every RF connector causes insertion loss, which refers to the decrease in signal strength when it passes through the connector.Rate this question:
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- 36.
When using an RF splitter to connect one transceiver to sector antennas loss is incurred. What is this loss called?
- A.
Through loss
- B.
Active loss
- C.
Conversion loss
- D.
Intentional loss
Correct Answer
A. Through lossExplanation
When using an RF splitter to connect one transceiver to sector antennas, some signal loss occurs. This loss is known as "through loss."Rate this question:
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- 37.
XYZ Corporation is experiencing connectivity problems with their existing building-to-building bridge link. A concrete wall on the roof of one building is partially blocking the Fresnel Zone, and the connection is dropping many frames. The administrator moves the antenna to an area not obstructed by the concrete wall and then realizes the RF cable cannot reach the new location. If an extension cable is added to move the antenna, what are the likely results?
- A.
The size of the Fresnel zone will increase.
- B.
The antenna’s azimuth beamwidth will decrease.
- C.
The data throughput rate will increase because VSWR will decrease.
- D.
The Equivalent Isotropically Radiated Power (EIRP) will decrease.
- E.
The likelihood of a direct lightning strike will increase
Correct Answer
D. The Equivalent Isotropically Radiated Power (EIRP) will decrease.Explanation
If an extension cable is added to move the antenna, the Equivalent Isotropically Radiated Power (EIRP) will decrease. This is because the extension cable will introduce additional loss and attenuation, reducing the overall power output of the antenna. As a result, the signal strength and coverage area will be reduced, impacting the connectivity and data throughput rate. The other options mentioned in the question, such as the size of the Fresnel zone, antenna's azimuth beamwidth, data throughput rate, and likelihood of a direct lightning strike, are not directly affected by adding an extension cable.Rate this question:
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- 38.
What is the intended use for the WLAN hardware known as a pole or mast mount unit?
- A.
Mounting an omnidirectional antenna to a mast
- B.
Mounting a lightning arrestor to a grounding rod
- C.
Mounting an RF amplifier to a dipole antenna
- D.
Mounting an access point to a site survey tripod
- E.
Mounting a PoE injector to a perforated radome
Correct Answer
A. Mounting an omnidirectional antenna to a mastExplanation
The intended use for the WLAN hardware known as a pole or mast mount unit is to mount an omnidirectional antenna to a mast. This allows for better signal coverage and range in all directions, as the antenna can be elevated and positioned for optimal performance.Rate this question:
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- 39.
Which answer correctly completes the following sentence? The WMM certification, created by the Wi-Fi Alliance, is based on the ___________ coordination function with support for ___________ QoS priority.
- A.
Point, scheduled
- B.
Hybrid, contention-based
- C.
Distributed, trigger-and-delivery
- D.
Enhanced, contention-free
- E.
Dynamic, distributed
Correct Answer
B. Hybrid, contention-basedExplanation
The correct answer is "Hybrid, contention-based". The sentence is discussing the WMM certification, which is based on a hybrid coordination function. This means that it combines both scheduled and contention-based methods for coordinating access to the wireless medium. The certification also supports QoS (Quality of Service) priority, which ensures that certain types of data traffic receive higher priority for transmission.Rate this question:
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- 40.
What component of the 802.11 standard allows stations to reserve access to the RF medium for a specified period of time?
- A.
Listen Interval
- B.
RTS or CTS frames
- C.
Probe Request frames
- D.
DTIM Interval
- E.
Short guard intervals
Correct Answer
B. RTS or CTS framesExplanation
RTS (Request to Send) or CTS (Clear to Send) frames are used in the 802.11 standard to allow stations to reserve access to the RF (Radio Frequency) medium for a specified period of time. When a station wants to transmit data, it sends an RTS frame to the access point, requesting permission to transmit. The access point responds with a CTS frame, granting permission and reserving the medium. This mechanism helps to avoid collisions and ensures that the medium is available for the transmitting station for the specified duration.Rate this question:
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- 41.
In an 802.11n WLAN with a heterogeneous set of associated client devices including 802.11b, 11g, and 11n, what HT protection mode will the BSS use?
- A.
Mode 0: No protection mode (Greenfield
- B.
Mode 3: Non-HT mixed mode
- C.
Mode 1: Nonmember protection mode
- D.
Mode 2: 20 MHz protection mode
Correct Answer
B. Mode 3: Non-HT mixed modeExplanation
In an 802.11n WLAN with a heterogeneous set of associated client devices including 802.11b, 11g, and 11n, the BSS will use Mode 3: Non-HT mixed mode. This mode is used to provide backward compatibility for older devices that do not support HT (High Throughput) rates. It allows the BSS to operate in a mixed mode, supporting both non-HT devices and HT devices. This ensures that all devices can communicate effectively within the WLAN network.Rate this question:
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- 42.
What statement about 802.11 WLAN performance is true?
- A.
BSS support for 65 KB A-MPDUs will increase the maximum data rate available to client devices.
- B.
Use of larger frame sizes results in greater throughput in low interference environments.
- C.
In 802.11ac, changing the security mechanism from WPA2-Personal to WPA2-Enterprise will enable the VHT MCS rates
- D.
Compared to an Independent BSS, an Infrastructure BSS can provide almost twice the throughput between wireless nodes.
- E.
Use of short guard intervals improves reliability and throughput in high multipath environments
Correct Answer
B. Use of larger frame sizes results in greater throughput in low interference environments.Explanation
The statement that says "Use of larger frame sizes results in greater throughput in low interference environments" is true. In a low interference environment, using larger frame sizes allows for more data to be transmitted in each frame, resulting in higher throughput. This is because larger frames have less overhead compared to smaller frames, which improves the efficiency of data transmission. However, in high interference environments, larger frames may be more prone to errors and may result in lower throughput.Rate this question:
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- 43.
The 802.11 protocol specifies a fundamental channel access method that is required for all stations and is used in all IBSS and BSS networks. What is this fundamental channel access method called?
- A.
PCF
- B.
HCF
- C.
DCF
- D.
EDCAF
- E.
HCCA
- F.
PCF/CA
Correct Answer
C. DCFExplanation
The fundamental channel access method specified by the 802.11 protocol is called DCF (Distributed Coordination Function). This method is required for all stations and is used in both IBSS (Independent Basic Service Set) and BSS (Basic Service Set) networks. DCF uses a contention-based approach where stations contend for access to the channel by sensing its availability and waiting for a clear channel before transmitting data. This method helps ensure fair and efficient access to the wireless channel for all stations in the network.Rate this question:
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- 44.
What mechanisms are specified by the IEEE 802.11 standard to attempt to prevent multiple radios from transmitting on the RF medium at a given point in time? (Choose 3)
- A.
Collision detection
- B.
Random backoff timer
- C.
Clear channel assessment
- D.
Slot assessment value
- E.
Network allocation vector
Correct Answer(s)
B. Random backoff timer
C. Clear channel assessment
E. Network allocation vectorExplanation
The IEEE 802.11 standard specifies three mechanisms to prevent multiple radios from transmitting on the RF medium at the same time.
1. Random backoff timer: This mechanism introduces a random delay before a station attempts to retransmit after a collision. It helps to avoid repeated collisions by ensuring that stations do not attempt to transmit simultaneously.
2. Clear channel assessment: This mechanism allows a station to sense the medium before transmitting. It checks if the channel is busy or idle, and if it detects activity, it waits until the channel is clear before transmitting.
3. Network allocation vector: This mechanism is used in the Distributed Coordination Function (DCF) of the IEEE 802.11 standard. It is a counter that is used to schedule transmissions and prevent multiple stations from transmitting simultaneously. Stations must wait until their allocated time slot before transmitting.Rate this question:
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- 45.
The client devices that connect to your network include a mix of dual-band 802.11n and 802.11ac, single-band 802.11b/g/n, and some 802.11a/g/n. Your access points are configured with the same SSID on both the 2.4 and 5 GHz bands. The APs are also configured to prioritize client connectivity to 5 GHz. How does an AP perform band steering to encourage clients to use 5 GHz?
- A.
When the client sends a probe request in the 2.4 GHz band, the AP may reply with information about the 5 GHz BSS.
- B.
The AP may allow an 802.11 association with the client in the 2.4 GHz band, then send unicast channel switch announcements to the client announcing the 5 GHz channel as the new channel.
- C.
The AP may ignore the initial probe requests or 802.11 authentication requests sent in the 2.4 GHz band by dual-band clients
- D.
After receiving probe request frames from the same client in both bands, the AP may send an association request frame to the client in the 5 GHz band.
- E.
The AP may allow an 802.11 association with the client in the 2.4 GHz band, then the AP may perform a transparent client handoff by transferring the client’s MAC address to the 5 GHz radio.
Correct Answer
C. The AP may ignore the initial probe requests or 802.11 authentication requests sent in the 2.4 GHz band by dual-band clientsExplanation
The AP may ignore the initial probe requests or 802.11 authentication requests sent in the 2.4 GHz band by dual-band clients. This means that when a client device sends a probe request or authentication request in the 2.4 GHz band, the AP will not respond or acknowledge these requests. By ignoring these requests, the AP is essentially discouraging the client from using the 2.4 GHz band and encouraging them to connect to the 5 GHz band instead. This helps to steer clients towards the 5 GHz band, which typically offers faster speeds and less interference compared to the 2.4 GHz band.Rate this question:
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- 46.
What information is transmitted in the Beacon management frames of an HT access point to communicate about backward compatibility with ERP and HR/DSSS stations? (Choose 2)
- A.
RIFS mode
- B.
Secondary channel offset
- C.
HT Protection mode
- D.
Non-ERP Present field
- E.
Power save mode of clients
Correct Answer(s)
C. HT Protection mode
D. Non-ERP Present fieldExplanation
The Beacon management frames of an HT access point transmit information about backward compatibility with ERP and HR/DSSS stations through the HT Protection mode and Non-ERP Present field. The HT Protection mode is used to indicate whether the access point supports protection mechanisms for legacy stations. The Non-ERP Present field is used to indicate the presence of non-HT stations in the network, allowing the access point to adjust its behavior accordingly to maintain compatibility.Rate this question:
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- 47.
What feature(s) are most likely to be supported by 802.11 enterprise-class WLAN controllers? (Choose 4)
- A.
BGP and Frame Relay
- B.
Link aggregation / port trunking
- C.
802.1p and DSCP QoS
- D.
Captive web portals
- E.
IGMP snooping
Correct Answer(s)
B. Link aggregation / port trunking
C. 802.1p and DSCP QoS
D. Captive web portals
E. IGMP snoopingExplanation
802.11 enterprise-class WLAN controllers are likely to support link aggregation/port trunking, 802.1p and DSCP QoS, captive web portals, and IGMP snooping. Link aggregation/port trunking allows multiple network links to be combined to increase bandwidth and provide redundancy. 802.1p and DSCP QoS enable prioritization and quality of service for different types of network traffic. Captive web portals are used for guest authentication and access control. IGMP snooping helps manage multicast traffic by allowing the controller to listen in on IGMP messages and forward multicast traffic only to the appropriate devices.Rate this question:
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- 48.
ABC Company has thousands of Wi-Fi users accessing their network on a daily basis. Their WLAN consists of 700 access points, 6 WLAN controllers, and a wireless network management system. What network functions are performed by the enterprise-class WNMS? (Choose 3)
- A.
Management of WLAN controller configuration and provisioning of firmware updates
- B.
RF pre-deployment planning and post-deployment reporting of access point locations on a floor plan
- C.
Radio management, fast roaming, key caching, and other centralized control plane operations
- D.
Performance and security monitoring of WLAN controllers with alarms and notifications for administrative staff
- E.
Centralized bridging of guest data traffic and application of firewall and QoS policies to data
- F.
Generating, encrypting, and decrypting 802.11 frames and collecting RF radio data.
Correct Answer(s)
A. Management of WLAN controller configuration and provisioning of firmware updates
B. RF pre-deployment planning and post-deployment reporting of access point locations on a floor plan
D. Performance and security monitoring of WLAN controllers with alarms and notifications for administrative staffExplanation
The enterprise-class WNMS performs three network functions: management of WLAN controller configuration and provisioning of firmware updates, RF pre-deployment planning and post-deployment reporting of access point locations on a floor plan, and performance and security monitoring of WLAN controllers with alarms and notifications for administrative staff. These functions allow ABC Company to efficiently manage their WLAN network, ensure proper deployment and coverage of access points, and monitor the performance and security of the network for optimal user experience.Rate this question:
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- 49.
In a Wi-Fi client configuration utility, what feature is most likely to be user configurable?
- A.
802.1p to WMM mappings
- B.
SNMPv3 Users
- C.
WMM-PS Dozing Interval
- D.
RADIUS Server IP Address
- E.
EAP Authentication Type
Correct Answer
E. EAP Authentication TypeExplanation
In a Wi-Fi client configuration utility, the feature that is most likely to be user configurable is the EAP Authentication Type. This is because the EAP (Extensible Authentication Protocol) is used for secure authentication in Wi-Fi networks, and different types of EAP methods can be used depending on the network's security requirements. Therefore, the user would need to configure the EAP Authentication Type to match the authentication method used by the network they are connecting to.Rate this question:
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- 50.
What is a common feature of an 802.11 WLAN client utility? (Choose 2)
- A.
Real-time retry monitor
- B.
AP Signal strength meter
- C.
Spectrum analyzer utility
- D.
VLAN configuration
- E.
Link statistics display
Correct Answer(s)
B. AP Signal strength meter
E. Link statistics displayExplanation
A common feature of an 802.11 WLAN client utility is the AP signal strength meter, which allows the client to measure and display the strength of the signal from the access point. This helps the client determine the quality of the connection and choose the best access point to connect to. Another common feature is the link statistics display, which provides information about the performance of the wireless link, such as the data rate, signal quality, and error rate. This helps the client monitor the health of the connection and troubleshoot any issues.Rate this question:
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Mar 21, 2023Quiz Edited by
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