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HCIA-WLAN practice questions

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Question 1WLAN Fundamentals and Standards

Which IEEE 802.11 amendment introduced OFDM as the physical-layer technology for the 5 GHz band and defined data rates up to 54 Mbit/s?

  1. 802.11b
  2. 802.11n
  3. 802.11a Correct answer.
  4. 802.11g

Explanation

802.11a operates in the 5 GHz band and uses OFDM with a maximum rate of 54 Mbit/s. 802.11b uses DSSS/CCK in 2.4 GHz at up to 11 Mbit/s, while 802.11g applies OFDM in 2.4 GHz. 802.11n added MIMO and wider channels but is not the original OFDM-at-5-GHz amendment.

Question 2WLAN Fundamentals and Standards

A wireless client associates to an AP and the two sides exchange keys during a 4-way handshake. Which security mechanism does this handshake belong to?

  1. WEP with shared-key authentication
  2. Open system authentication with MAC filtering
  3. Captive portal web authentication
  4. WPA2-PSK or WPA2-Enterprise using 802.11i Correct answer.

Explanation

The 4-way handshake is defined by 802.11i (WPA2) and is used to derive and confirm the pairwise transient key after 802.1X or PSK authentication. It applies to both personal and enterprise modes. WEP, open authentication, and web portals do not use this handshake.

Question 3WLAN Fundamentals and Standards

Which organization is responsible for publishing the 802.11 family of WLAN standards?

  1. 3GPP
  2. Wi-Fi Alliance
  3. IETF
  4. IEEE Correct answer.

Explanation

The IEEE develops and publishes the 802.11 standards that define WLAN PHY and MAC behavior. The Wi-Fi Alliance performs certification and interoperability testing rather than writing the standards. 3GPP covers cellular specifications and IETF covers Internet protocols.

Question 4WLAN Fundamentals and Standards

Which frequency band does an 802.11b/g/n (2.4 GHz) WLAN use, and how many non-overlapping 20 MHz channels are typically available in it?

  1. 5 GHz band with 3 non-overlapping channels
  2. 2.4 GHz band with 3 non-overlapping channels Correct answer.
  3. 2.4 GHz band with 11 non-overlapping channels
  4. 5 GHz band with 19 non-overlapping channels

Explanation

The 2.4 GHz ISM band spans roughly 2.4 to 2.4835 GHz, and channel spacing of 5 MHz with 20 MHz channel width leaves only three non-overlapping channels (1, 6, and 11 in most regulatory domains). The 5 GHz band offers many more non-overlapping channels.

Question 5WLAN Fundamentals and Standards

What is the primary purpose of a beacon frame in an 802.11 BSS?

  1. To carry user data from a client to the distribution system
  2. To report a frame checksum error back to the sender
  3. To request a channel access reservation from the AP
  4. To advertise the SSID and network parameters so clients can discover the BSS Correct answer.

Explanation

Beacon frames are management frames transmitted periodically by the AP to announce the BSS, including SSID, supported rates, and security parameters. Clients use them for passive scanning and to learn when the network is available. Data transport and error reporting are handled by other frame types.

Question 6WLAN Fundamentals and Standards

Which modulation and coding scheme is used by 802.11ac to achieve its highest throughput rates?

  1. DSSS with Barker coding
  2. FHSS with GFSK
  3. CCK with up to 64-QAM
  4. OFDM with up to 256-QAM and wider channels Correct answer.

Explanation

802.11ac (Very High Throughput) operates in 5 GHz using OFDM with up to 256-QAM, wider 80 and 160 MHz channels, and downlink MU-MIMO. These features together produce its high data rates. DSSS, FHSS, and CCK are legacy 2.4 GHz techniques.

Question 7WLAN Fundamentals and Standards

Which term describes the logical grouping of wireless clients that associate to a single access point and share its BSSID?

  1. BSS Correct answer.
  2. DS
  3. ESS
  4. IBSS

Explanation

A Basic Service Set (BSS) is the fundamental building block of an 802.11 network: clients associated with one AP identified by a BSSID. An ESS joins multiple BSSs through a distribution system, while an IBSS is an ad hoc network without an AP.

Question 8WLAN Fundamentals and Standards

In an 802.11 infrastructure network, which frame is sent by a client to begin the association process with an AP after discovery?

  1. Association request Correct answer.
  2. Probe request
  3. Reassociation request
  4. Authentication request

Explanation

After discovery and successful authentication, a client sends an association request to the AP, which replies with an association response assigning an association ID. Probe requests are used during discovery, and authentication must precede association. Reassociation is used when a client moves between APs.

Question 9WLAN Fundamentals and Standards

A company wants to deploy 802.11ax in a dense office and needs to know which feature improves efficiency when many clients transmit small frames. Which 802.11ax mechanism addresses this?

  1. Use of 802.11b protection frames
  2. Reduction of the guard interval to zero
  3. Larger 160 MHz channels only
  4. OFDMA with resource-unit scheduling Correct answer.

Explanation

802.11ax introduces OFDMA, which divides a channel into resource units so multiple clients can transmit simultaneously in the uplink or downlink, reducing contention overhead for small frames. Wider channels alone do not solve dense-client inefficiency, and the guard interval cannot be reduced to zero.

Question 10WLAN Fundamentals and Standards

An administrator observes that a client on channel 6 experiences interference from a neighboring network on channel 8. Which statement best explains the problem?

  1. Channel 8 is illegal in the 2.4 GHz band and cannot cause interference
  2. Channels 6 and 8 overlap because 20 MHz channels spaced 5 MHz apart share spectrum Correct answer.
  3. Channels 6 and 8 are non-overlapping, so the interference must come from another source
  4. Interference only occurs between channels in different bands

Explanation

In the 2.4 GHz band, 20 MHz channels are spaced 5 MHz apart, so channels 6 and 8 overlap substantially and contend for the same spectrum. Only channels spaced at least 25 MHz apart, such as 1, 6, and 11, avoid overlap. Interference is not restricted to different bands.

Question 11WLAN Fundamentals and Standards

A WLAN uses WPA2-Enterprise. Which sequence correctly describes how a supplicant gains network access?

  1. PSK exchange, 4-way handshake, DHCP
  2. 802.1X/EAP authentication with a RADIUS server, then 4-way handshake Correct answer.
  3. Captive portal login, then TKIP key rotation
  4. Open authentication, then WEP key exchange

Explanation

WPA2-Enterprise uses 802.1X with an EAP method to authenticate the client against a RADIUS server, after which the 4-way handshake derives and installs the pairwise keys. PSK is used in personal mode, and WEP or captive portals are unrelated to WPA2-Enterprise.

Question 12WLAN Fundamentals and Standards

Which field in an 802.11 MAC header indicates whether the frame is a management, control, or data frame?

  1. FCS field
  2. Duration/ID field
  3. Frame Control Type and Subtype fields Correct answer.
  4. Sequence Control field

Explanation

The Frame Control field contains Type and Subtype subfields that classify a frame as management, control, or data and identify its specific function. The Duration/ID field carries timing information, Sequence Control handles fragmentation and ordering, and the FCS is a checksum.

Question 13WLAN Fundamentals and Standards

A client roams from AP-1 to AP-2 within the same ESS. Which frame does the client send to AP-2 to resume connectivity while retaining its security context?

  1. Authentication request
  2. Probe request
  3. Beacon frame
  4. Reassociation request Correct answer.

Explanation

When roaming within an ESS, the client sends a reassociation request to the new AP, which transfers the association and informs the old AP through the distribution system. This preserves the client's session and, with fast roaming mechanisms, its security context. Beacons are sent by APs, not clients.

Question 14WLAN Fundamentals and Standards

Which statement accurately describes the difference between MIMO and MU-MIMO in 802.11?

  1. MU-MIMO uses a single antenna, while MIMO uses several antennas
  2. MIMO serves one client with multiple spatial streams, while MU-MIMO serves multiple clients simultaneously Correct answer.
  3. MIMO and MU-MIMO are identical and differ only in marketing terminology
  4. MIMO requires 5 GHz, while MU-MIMO only works in 2.4 GHz

Explanation

Single-user MIMO uses multiple antennas to send multiple spatial streams to one client, increasing that client's throughput. MU-MIMO divides the spatial resources among several clients at the same time, improving aggregate efficiency. Both rely on multiple antennas at the AP.

Question 15WLAN Fundamentals and Standards

Which 802.11 amendment first introduced operation in the 60 GHz millimeter-wave band with very wide channels?

  1. 802.11ax
  2. 802.11n
  3. 802.11ac
  4. 802.11ad Correct answer.

Explanation

802.11ad (DMG) defines operation in the 60 GHz band using channels of about 2 GHz width to achieve multi-gigabit rates over short distances. 802.11n and 802.11ac operate in 2.4 and 5 GHz, and 802.11ax focuses on efficiency in sub-7 GHz bands.

Question 16WLAN Fundamentals and Standards

A network engineer must choose a channel plan for a 2.4 GHz deployment with three APs in close proximity. Which set of channels minimizes co-channel and adjacent-channel interference?

  1. 1, 6, and 11 Correct answer.
  2. 1, 2, and 3
  3. 1, 5, and 9
  4. 2, 4, and 6

Explanation

Channels 1, 6, and 11 are separated by 25 MHz, so their 20 MHz channels do not overlap and they can be reused with minimal interference. Sets spaced only 5 or 10 MHz apart overlap and cause adjacent-channel interference.

Question 17WLAN Fundamentals and Standards

Which mechanism in 802.11 allows a station to save power by sleeping and waking to receive buffered frames?

  1. Fragmentation
  2. Block acknowledgment
  3. RTS/CTS
  4. Power Save mode with TIM/DTIM in beacons Correct answer.

Explanation

In power save mode a station may sleep, and the AP buffers frames for it. The TIM and DTIM fields in beacons indicate whether buffered traffic exists and when multicast or broadcast frames will be delivered, so the station knows when to wake. RTS/CTS, fragmentation, and block ACK address medium access and reliability, not power saving.

Question 18WLAN Fundamentals and Standards

What is the main purpose of the CSMA/CA mechanism in 802.11?

  1. To detect collisions by measuring signal voltage on the medium
  2. To avoid collisions by sensing the medium and using random backoff before transmitting Correct answer.
  3. To encrypt frames before they are sent over the air
  4. To assign IP addresses to associated clients

Explanation

Wireless stations cannot reliably detect collisions while transmitting, so 802.11 uses carrier sense multiple access with collision avoidance: it senses the medium, waits a random backoff, and uses optional RTS/CTS. Encryption and addressing are handled by other mechanisms.

Question 19WLAN Fundamentals and Standards

Which EAP method is commonly deployed in WPA2-Enterprise because it provides mutual authentication using server certificates and is widely supported?

  1. EAP-TLS or PEAP with server certificate validation Correct answer.
  2. Open system authentication
  3. WEP with shared key
  4. TKIP with Michael MIC

Explanation

EAP-TLS uses certificates on both client and server, and PEAP establishes a TLS tunnel protected by a server certificate, so both provide mutual authentication and are widely supported in WPA2-Enterprise. WEP, TKIP, and open authentication are legacy or non-802.1X schemes.

Question 20WLAN Fundamentals and Standards

An AP advertises an SSID but hides it by omitting the SSID from beacons. Which statement best describes the security value of this configuration?

  1. It prevents all clients from associating to the network
  2. It offers only marginal obscurity because the SSID can still be learned from probe and association frames Correct answer.
  3. It provides strong encryption equivalent to WPA2
  4. It disables the 4-way handshake

Explanation

Hidden SSIDs do not encrypt traffic or authenticate users; the SSID still appears in probe requests, probe responses, and association frames, so it can be discovered easily. Real protection comes from authentication and encryption such as WPA2 or WPA3.

Question 21WLAN Fundamentals and Standards

Which statement correctly describes the relationship between an ESS and a BSS?

  1. An ESS is formed by multiple BSSs connected through a distribution system under one SSID Correct answer.
  2. An ESS consists of one BSS with a single AP
  3. A BSS is formed by multiple ESSs sharing a BSSID
  4. An ESS requires no access points and operates in ad hoc mode

Explanation

An Extended Service Set joins several Basic Service Sets through a distribution system, typically presenting one SSID so clients can roam between APs. A single BSS is one AP with its associated clients, and ad hoc operation is an IBSS rather than an ESS.

Question 22WLAN Fundamentals and Standards

A station using 802.11ac with 80 MHz channel width and 2 spatial streams is compared with a station using 802.11n with 40 MHz and 2 streams. Which factor most directly explains the higher peak rate of the 802.11ac station?

  1. The use of a lower frequency band
  2. The combination of wider channel width and higher-order 256-QAM modulation Correct answer.
  3. The use of DSSS instead of OFDM
  4. A longer guard interval

Explanation

802.11ac peak rates come from wider channels (80 or 160 MHz) and 256-QAM, which carries more bits per subcarrier than the 64-QAM used in 802.11n. Frequency band and a longer guard interval do not increase throughput, and 802.11ac uses OFDM rather than DSSS.

Question 23WLAN Fundamentals and Standards

Which statement best explains why 802.11ax introduces BSS coloring?

  1. It replaces CSMA/CA with a scheduled TDMA scheme
  2. It increases the maximum channel width to 320 MHz
  3. It encrypts beacons to prevent SSID spoofing
  4. It tags frames with a color value so stations can distinguish overlapping BSS transmissions and reduce unnecessary deferral Correct answer.

Explanation

BSS coloring adds a color field to the PHY header so a station can tell whether a detected transmission belongs to its own BSS or an overlapping one. Frames from a different color may be treated with a higher CCA threshold, reducing unnecessary deferral in dense deployments. It is not encryption, scheduling, or a channel-width feature.

Question 24WLAN Fundamentals and Standards

A client repeatedly sends RTS frames but receives no CTS from the AP, and its data frames fail. Which conclusion is most consistent with these observations?

  1. The client has successfully reserved the channel and the failure is at layer 3
  2. The AP is not receiving the client's RTS, indicating an asymmetric link or hidden-node condition Correct answer.
  3. The client is using the wrong encryption key
  4. The AP has disabled beacon transmission

Explanation

In RTS/CTS the AP must hear the RTS and reply with a CTS before the client may transmit. If no CTS arrives, the AP likely did not receive the RTS, which points to an asymmetric radio link or a hidden-node situation. Encryption and beacon settings would not selectively block CTS replies.

Question 25WLAN Fundamentals and Standards

Which statement best describes the role of the distribution system in an ESS?

  1. It encrypts all management frames with WPA3
  2. It performs 802.1X authentication for wireless clients
  3. It carries frames between APs so clients can communicate across BSSs and roam Correct answer.
  4. It assigns 2.4 GHz channels to each AP automatically

Explanation

The distribution system is the wired or wireless backbone that connects APs in an ESS, allowing frames to be forwarded between BSSs and supporting roaming. Authentication, channel assignment, and management-frame protection are separate functions performed by other components.

Question 26WLAN Fundamentals and Standards

Which 802.11 amendment is the basis for the original Wi-Fi certification in the 2.4 GHz band with rates up to 2 Mbps?

  1. 802.11a
  2. 802.11g
  3. 802.11b
  4. 802.11 Correct answer.

Explanation

The original 802.11 standard, ratified in 1997, defined 1 and 2 Mbps operation in the 2.4 GHz band using FHSS and DSSS. Later amendments such as 802.11b added higher rates.

Question 27WLAN Fundamentals and Standards

Which frequency band does 802.11a use?

  1. 5 GHz Correct answer.
  2. 900 MHz
  3. 60 GHz
  4. 2.4 GHz

Explanation

802.11a was defined for the 5 GHz band and uses OFDM to achieve up to 54 Mbps. It avoids the crowded 2.4 GHz band but has shorter range at the same power.

Question 28WLAN Fundamentals and Standards

Which 802.11 amendment introduced OFDM to the 2.4 GHz band and is backward compatible with 802.11b?

  1. 802.11a
  2. 802.11n
  3. 802.11g Correct answer.
  4. 802.11ac

Explanation

802.11g operates in the 2.4 GHz band using OFDM for rates up to 54 Mbps and includes ERP protection mechanisms to coexist with 802.11b devices. 802.11a uses OFDM but only in 5 GHz.

Question 29WLAN Fundamentals and Standards

Which 802.11 amendment is marketed as Wi-Fi 6?

  1. 802.11ac
  2. 802.11ax Correct answer.
  3. 802.11n
  4. 802.11ad

Explanation

The Wi-Fi Alliance designated 802.11ax as Wi-Fi 6, reflecting its focus on high-efficiency operation in dense environments. 802.11ac is Wi-Fi 5, and 802.11n is Wi-Fi 4.

Question 30WLAN Fundamentals and Standards

What is the maximum channel width defined by 802.11ac?

  1. 40 MHz
  2. 160 MHz Correct answer.
  3. 80 MHz
  4. 320 MHz

Explanation

802.11ac supports 20, 40, 80, and 160 MHz channels, with 160 MHz being the maximum. 320 MHz channels were introduced later by 802.11be.

Question 31WLAN Fundamentals and Standards

Which 802.11 frame type is used for association and authentication?

  1. Management Correct answer.
  2. Extension
  3. Control
  4. Data

Explanation

Management frames include beacon, probe request/response, authentication, association, and deauthentication. They establish and maintain the relationship between a station and an AP.

Question 32WLAN Fundamentals and Standards

Which 802.11 frame is broadcast periodically by an AP to advertise the SSID and supported capabilities?

  1. Association response
  2. Probe request
  3. Beacon Correct answer.
  4. Authentication

Explanation

The beacon frame is transmitted at a fixed interval (typically 100 ms) and carries the SSID, supported rates, and other capability information. Clients use beacons to discover and compare networks.

Question 33WLAN Fundamentals and Standards

Which mechanism does 802.11 use to avoid collisions on the wireless medium?

  1. CSMA/CD
  2. TDMA
  3. CSMA/CA Correct answer.
  4. Token passing

Explanation

802.11 uses Carrier Sense Multiple Access with Collision Avoidance because a station cannot reliably detect collisions while transmitting. It uses random backoff and optional RTS/CTS to reduce collision probability.

Question 34WLAN Fundamentals and Standards

Which 802.11 amendment introduced MIMO and operates in both 2.4 GHz and 5 GHz bands?

  1. 802.11a
  2. 802.11n Correct answer.
  3. 802.11g
  4. 802.11ac

Explanation

802.11n introduced MIMO, wider 40 MHz channels, and operation in both the 2.4 GHz and 5 GHz bands. It is marketed as Wi-Fi 4.

Question 35WLAN Fundamentals and Standards

Which term describes the 48-bit address that uniquely identifies a wireless station or AP interface?

  1. IP address
  2. MAC address Correct answer.
  3. BSSID
  4. SSID

Explanation

The MAC address is a 48-bit identifier assigned to a network interface and used in 802.11 frame headers. The BSSID is the MAC address of an AP's radio, but the general term for the hardware address is MAC address.

Question 36WLAN Fundamentals and Standards

Which 802.11 amendment introduced the 60 GHz millimeter-wave band with channels up to 2.16 GHz wide?

  1. 802.11ax
  2. 802.11ac
  3. 802.11ad Correct answer.
  4. 802.11af

Explanation

802.11ad, also known as WiGig, operates in the 60 GHz band and defines channels up to 2.16 GHz wide for very high throughput over short distances. It is not backward compatible with 2.4 or 5 GHz devices.

Question 37WLAN Fundamentals and Standards

Which statement correctly describes the relationship between an SSID and a BSSID?

  1. The BSSID is assigned by DHCP, while the SSID is configured on the AP.
  2. The SSID is a network name, and the BSSID is the MAC address of the AP radio serving that network. Correct answer.
  3. The SSID is the AP radio's MAC address, and the BSSID is the network name.
  4. Both the SSID and BSSID are 48-bit hardware addresses.

Explanation

The SSID is a human-readable network name of up to 32 bytes, while the BSSID is the 48-bit MAC address of the AP radio that anchors a BSS. Multiple BSSIDs can advertise the same SSID in an ESS.

Question 38WLAN Fundamentals and Standards

Which frame does a client send to discover nearby APs without waiting for a beacon?

  1. Reassociation request
  2. Probe request Correct answer.
  3. Association request
  4. Beacon

Explanation

A probe request is sent by a client to solicit information from APs; APs reply with probe responses. Active scanning uses probe requests, while passive scanning relies on beacons.

Question 39WLAN Fundamentals and Standards

An AP is configured with a 40 MHz channel in the 2.4 GHz band. Which statement best describes the likely effect on neighboring networks?

  1. It has no effect because 40 MHz is not allowed in 2.4 GHz.
  2. It reduces co-channel interference because the wider channel spreads energy.
  3. It occupies a large portion of the band and increases the chance of overlapping-channel interference. Correct answer.
  4. It automatically selects the least congested 20 MHz subchannel for neighbors.

Explanation

A 40 MHz channel in 2.4 GHz consumes roughly eight of the fourteen overlapping 20 MHz channels, leaving little room for neighbors. This increases the likelihood of overlapping-channel interference and is generally discouraged in dense deployments.

Question 40WLAN Fundamentals and Standards

Which 802.11ac feature allows an AP to transmit to multiple clients simultaneously in the downlink direction?

  1. MU-MIMO Correct answer.
  2. SU-MIMO
  3. Channel bonding
  4. Beamforming

Explanation

Downlink MU-MIMO in 802.11ac allows an AP to send separate spatial streams to multiple clients at the same time. SU-MIMO serves only one client at a time, and beamforming improves signal to a single client.

Question 41WLAN Fundamentals and Standards

Which statement best describes the purpose of the 802.11 ACK frame?

  1. It announces the SSID to new clients.
  2. It requests the medium for a station before transmission.
  3. It carries authentication credentials to the AP.
  4. It confirms successful reception of a unicast data frame. Correct answer.

Explanation

The ACK frame is a control frame sent by the receiver to confirm that a unicast data frame was received correctly. If the sender does not receive an ACK within the timeout, it retransmits the frame.

Question 42WLAN Fundamentals and Standards

A station is configured with a 20 MHz channel and 2 spatial streams using 802.11n. Which factor most directly limits its maximum data rate?

  1. The SSID length restricts the achievable throughput.
  2. The beacon interval sets the maximum frame size.
  3. The authentication method determines the modulation scheme.
  4. The number of spatial streams and channel width determine the maximum MCS rate. Correct answer.

Explanation

In 802.11n, the maximum data rate depends on the MCS, which combines modulation, coding rate, channel width, and number of spatial streams. With 20 MHz and two streams, the rate is capped accordingly.

Question 43WLAN Fundamentals and Standards

Which 802.11 mechanism allows a station to sleep and have the AP buffer frames for later delivery?

  1. RTS/CTS
  2. Power save mode with TIM/DTIM Correct answer.
  3. Frame aggregation
  4. Block ACK

Explanation

A station in power save mode informs the AP and sleeps; the AP buffers frames and indicates them in the TIM, with DTIM indicating broadcast/multicast delivery. The station wakes at the DTIM interval to retrieve buffered traffic.

Question 44WLAN Fundamentals and Standards

Which security improvement does WPA2 introduce over WPA?

  1. It replaces 802.1X with a preshared key in enterprise mode.
  2. It removes the need for a passphrase in personal mode.
  3. It uses WEP for backward compatibility.
  4. It mandates AES-CCMP instead of TKIP for encryption. Correct answer.

Explanation

WPA2 requires AES-CCMP for confidentiality and integrity, which is stronger than the TKIP used by WPA. WPA2 still supports both personal (PSK) and enterprise (802.1X) modes.

Question 45WLAN Fundamentals and Standards

Which 802.11ax feature improves efficiency by allowing overlapping BSSs to reuse the same channel based on color markings?

  1. MU-MIMO
  2. Target wake time
  3. BSS coloring Correct answer.
  4. OFDMA

Explanation

BSS coloring adds a 6-bit color to the PHY header so a station can distinguish its own BSS from overlapping BSSs and ignore interference from different colors. This enables spatial reuse and reduces unnecessary backoff.

Question 46WLAN Fundamentals and Standards

Which statement best explains why 802.11ax introduces OFDMA in the uplink direction?

  1. It replaces CSMA/CA with a scheduled TDMA scheme for all traffic.
  2. It doubles the channel width to 320 MHz for higher peak rates.
  3. It allows multiple stations to transmit simultaneously on different resource units, reducing contention overhead. Correct answer.
  4. It increases the transmit power of each station to improve range.

Explanation

Uplink OFDMA lets the AP schedule multiple stations to transmit at the same time on separate resource units, which reduces contention and improves efficiency in dense environments. It does not replace CSMA/CA entirely or increase channel width.

Question 47WLAN Fundamentals and Standards

A client roams from AP-1 to AP-2 in the same ESS. Which frame does the client send to AP-2 to resume connectivity while retaining its association context?

  1. Reassociation request Correct answer.
  2. Authentication request
  3. Probe request
  4. Association request

Explanation

A reassociation request is sent to a new AP in the same ESS and includes the current AP's address so the distribution system can forward buffered frames. A plain association request is used for initial association, not roaming.

Question 48WLAN Fundamentals and Standards

An engineer must choose a 2.4 GHz channel plan for three APs in close proximity. Which set of channels provides non-overlapping operation?

  1. 1, 5, 9
  2. 1, 2, 3
  3. 1, 6, 11 Correct answer.
  4. 2, 4, 6

Explanation

In the 2.4 GHz band, channels 1, 6, and 11 are the conventional non-overlapping set because each is separated by five channels. Other combinations such as 1, 5, 9 still overlap and cause co-channel or adjacent-channel interference.

Question 49WLAN Fundamentals and Standards

Which statement best explains why 802.11ac beamforming improves throughput for a single client?

  1. It widens the channel to 160 MHz automatically.
  2. It increases the number of spatial streams beyond the client's capability.
  3. It steers the transmitted signal toward the client, improving SNR and enabling a higher MCS. Correct answer.
  4. It removes the need for acknowledgment frames.

Explanation

Beamforming uses channel sounding to focus transmitted energy toward the client, raising the signal-to-noise ratio. A higher SNR allows the AP to select a more efficient modulation and coding scheme, increasing throughput.

Question 50WLAN Fundamentals and Standards

Which 802.11ax feature reduces power consumption by scheduling stations to wake at predetermined times?

  1. BSS coloring
  2. Target wake time Correct answer.
  3. Spatial reuse
  4. OFDMA

Explanation

Target wake time allows the AP to schedule a station's wake periods, reducing contention and saving battery power. BSS coloring and spatial reuse address interference, while OFDMA addresses multi-user efficiency.