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Aruba ACMA practice questions

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Question 1Aruba wireless architecture and product portfolio (Mobility Master/Mobility Controller, Instant AP, Aruba Central, gateways)

In ArubaOS 8, which function does the Mobility Master perform?

  1. It terminates CAP tunnels from all Instant APs
  2. It centrally manages configuration for Mobility Controllers Correct answer.
  3. It provides DHCP and DNS services to wireless clients
  4. It forwards client data traffic between APs and the Internet

Explanation

The Mobility Master is the management-plane entity in ArubaOS 8. It holds configuration, licensing, and policy that Mobility Controllers consume, while client traffic stays on the controllers.

Question 2Aruba wireless architecture and product portfolio (Mobility Master/Mobility Controller, Instant AP, Aruba Central, gateways)

In an Aruba Instant deployment, how is the virtual controller selected?

  1. By the DHCP server that assigns the AP management IP
  2. By an election among the Instant APs in the cluster Correct answer.
  3. By a static assignment configured in the Mobility Master
  4. By Aruba Central during device onboarding and provisioning

Explanation

Instant APs elect one member of the cluster to serve as the virtual controller. The election is automatic and does not depend on DHCP or a management platform.

Question 3Aruba wireless architecture and product portfolio (Mobility Master/Mobility Controller, Instant AP, Aruba Central, gateways)

Aruba Central is best described as which of the following?

  1. A standalone authentication server for 802.1X
  2. A cloud-based subscription service for managing Aruba devices Correct answer.
  3. An on-premises RF planning and site survey tool for Instant APs
  4. A hardware controller that terminates wireless client traffic

Explanation

Aruba Central is a cloud-delivered management platform offered by subscription. It provides configuration, monitoring, and troubleshooting rather than data-plane forwarding.

Question 4Aruba wireless architecture and product portfolio (Mobility Master/Mobility Controller, Instant AP, Aruba Central, gateways)

Which Aruba product family is designed for branch office WAN and security functions?

  1. Aruba 7000 series gateways Correct answer.
  2. Aruba 2900 series switches
  3. Aruba 7200 series Mobility Controllers
  4. Aruba Instant AP 500 series

Explanation

The Aruba 7000 series gateways are branch-oriented devices that combine routing, firewall, and VPN functions. The 7200 series is a Mobility Controller line for larger sites.

Question 5Aruba wireless architecture and product portfolio (Mobility Master/Mobility Controller, Instant AP, Aruba Central, gateways)

Which Aruba service provides zero-touch provisioning by directing devices to their management platform?

  1. Aruba Activate Correct answer.
  2. Aruba NetInsight
  3. Aruba ClearPass
  4. Aruba AirWave

Explanation

Aruba Activate is a cloud service that devices contact during first boot. It returns the management platform information needed to complete onboarding.

Question 6Aruba wireless architecture and product portfolio (Mobility Master/Mobility Controller, Instant AP, Aruba Central, gateways)

Which Aruba management product is deployed on-premises rather than as a cloud service?

  1. Aruba Central
  2. Aruba AirWave Correct answer.
  3. Aruba Activate
  4. Aruba Instant On

Explanation

Aruba AirWave is an on-premises network management platform. Central and Activate are cloud services, while Instant On is a product line for small businesses.

Question 7Aruba wireless architecture and product portfolio (Mobility Master/Mobility Controller, Instant AP, Aruba Central, gateways)

Which Aruba component terminates CAP tunnels and enforces role-based firewall policies for wireless clients?

  1. Mobility Master
  2. Mobility Controller Correct answer.
  3. Aruba Activate
  4. Aruba Central

Explanation

The Mobility Controller sits in the data path and terminates CAP tunnels from APs. It also applies role-based firewall policies to client traffic.

Question 8Aruba wireless architecture and product portfolio (Mobility Master/Mobility Controller, Instant AP, Aruba Central, gateways)

Which statement about an Aruba Instant AP cluster is true?

  1. It uses a Mobility Controller to terminate all client traffic
  2. One AP is elected to serve as the virtual controller Correct answer.
  3. It requires a dedicated hardware controller to authenticate all wireless clients
  4. It can only be managed by a Mobility Master

Explanation

An Instant cluster is controller-less by design, with one AP elected as the virtual controller. Management can come from Central, AirWave, or local standalone operation.

Question 9Aruba wireless architecture and product portfolio (Mobility Master/Mobility Controller, Instant AP, Aruba Central, gateways)

How does ArubaOS 8 differ from ArubaOS 6 in management architecture?

  1. Management and configuration move to a separate Mobility Master layer Correct answer.
  2. ArubaOS 8 requires every AP to run as an Instant AP
  3. ArubaOS 8 removes the need for any controller in large campus networks entirely
  4. ArubaOS 8 replaces Mobility Controllers with gateways only

Explanation

ArubaOS 8 separates the management plane, provided by the Mobility Master, from the data plane, provided by Mobility Controllers. ArubaOS 6 used a master controller among the controllers instead.

Question 10Aruba wireless architecture and product portfolio (Mobility Master/Mobility Controller, Instant AP, Aruba Central, gateways)

Aruba renamed the Mobility Master in ArubaOS 8 to which term?

  1. Mobility Director
  2. Mobility Orchestrator
  3. Mobility Gateway
  4. Mobility Conductor Correct answer.

Explanation

Aruba renamed the Mobility Master to Mobility Conductor while keeping the same management-plane role. The term appears in later ArubaOS 8 documentation and training.

Question 11Aruba wireless architecture and product portfolio (Mobility Master/Mobility Controller, Instant AP, Aruba Central, gateways)

In Aruba Central, what is the primary purpose of a group?

  1. The RADIUS server used to authenticate wireless users
  2. A configuration container that devices inherit settings from Correct answer.
  3. The IP address assigned to each device at boot
  4. The physical location of devices used for monitoring and maps

Explanation

A Central group is a configuration container; devices assigned to the group inherit its settings. Physical location is represented separately by a site.

Question 12Aruba wireless architecture and product portfolio (Mobility Master/Mobility Controller, Instant AP, Aruba Central, gateways)

In Aruba Central, which object is used to represent a physical location for monitoring and maps?

  1. Template
  2. Firmware
  3. Site Correct answer.
  4. Group

Explanation

A site in Central represents a physical location and is used for monitoring, maps, and location-based views. Groups, by contrast, control configuration inheritance.

Question 13Aruba wireless architecture and product portfolio (Mobility Master/Mobility Controller, Instant AP, Aruba Central, gateways)

When an Aruba device is first powered on for zero-touch onboarding, which service does it contact by default?

  1. The Mobility Master VRRP address
  2. The AirWave backup server
  3. The local ClearPass server
  4. Aruba Activate Correct answer.

Explanation

Devices are programmed to reach Aruba Activate during first boot for zero-touch provisioning. Activate then points the device to its assigned management platform.

Question 14Aruba wireless architecture and product portfolio (Mobility Master/Mobility Controller, Instant AP, Aruba Central, gateways)

Which statement describes converting an Aruba Instant AP to a Campus AP?

  1. The AP must be physically replaced with a controller-based AP model
  2. The AP keeps its Instant configuration and also joins a controller
  3. The AP changes mode so a Mobility Controller manages it Correct answer.
  4. The AP can only be converted by returning it to Aruba

Explanation

Conversion changes the AP operating mode so that it becomes a controller-managed Campus AP. The AP then builds a tunnel to and receives configuration from a Mobility Controller.

Question 15Aruba wireless architecture and product portfolio (Mobility Master/Mobility Controller, Instant AP, Aruba Central, gateways)

In an ArubaOS 8 deployment with a Mobility Master, where are licenses typically installed and pooled?

  1. On the Aruba Central subscription page only
  2. On the Mobility Master Correct answer.
  3. On each Mobility Controller separately
  4. On each Instant AP

Explanation

The Mobility Master centralizes license installation and pools capacity for the controllers it manages. This avoids licensing each controller independently.

Question 16Aruba wireless architecture and product portfolio (Mobility Master/Mobility Controller, Instant AP, Aruba Central, gateways)

What is the purpose of a standby Mobility Controller in ArubaOS 8?

  1. To terminate Instant AP tunnels in a controller-less design
  2. To act as the management plane for the Mobility Master appliance
  3. To provide a redundant controller that can take over on failure Correct answer.
  4. To host the Aruba Activate zero-touch service

Explanation

A standby controller provides redundancy for an active controller. It synchronizes state so that it can assume the active role if a failure occurs.

Question 17Aruba wireless architecture and product portfolio (Mobility Master/Mobility Controller, Instant AP, Aruba Central, gateways)

How is redundancy commonly provided between two Mobility Master instances?

  1. Using LACP to bond the management interfaces
  2. Using NAT to hide the standby unit
  3. Using STP to block one of the links
  4. Using VRRP to share a virtual IP address Correct answer.

Explanation

Mobility Master redundancy uses VRRP so that the pair presents a shared virtual IP address. If the active instance fails, the standby takes over that address.

Question 18Aruba wireless architecture and product portfolio (Mobility Master/Mobility Controller, Instant AP, Aruba Central, gateways)

Which statement about Aruba gateways and Aruba Central is correct?

  1. Gateways can be managed by Aruba Central as cloud devices Correct answer.
  2. Gateways can only be managed by a Mobility Master or AirWave
  3. Gateways require a Mobility Controller to forward traffic
  4. Gateways cannot be onboarded through Aruba Activate

Explanation

Aruba gateways can be onboarded to and managed through Aruba Central. They remain capable of forwarding traffic locally without relying on a separate controller.

Question 19Aruba wireless architecture and product portfolio (Mobility Master/Mobility Controller, Instant AP, Aruba Central, gateways)

Which management option is available for an Aruba Instant AP cluster?

  1. Only management through a Mobility Master
  2. Only management through AirWave
  3. Only standalone local management via the virtual controller
  4. Cloud management through Aruba Central Correct answer.

Explanation

Instant AP clusters can be managed through Aruba Central, AirWave, or locally through the virtual controller. Management is therefore not limited to a single platform.

Question 20Aruba wireless architecture and product portfolio (Mobility Master/Mobility Controller, Instant AP, Aruba Central, gateways)

In ArubaOS 8, how are configuration settings organized on the Mobility Master?

  1. As a flat list of commands applied identically to every managed controller
  2. As separate per-AP text files stored on each Instant AP
  3. As XML templates pushed only by Aruba Central
  4. As a hierarchy of configuration nodes that controllers can inherit from Correct answer.

Explanation

ArubaOS 8 organizes configuration into a hierarchy of nodes on the Mobility Master. Controllers are assigned to nodes and inherit settings from the hierarchy.

Question 21Aruba wireless architecture and product portfolio (Mobility Master/Mobility Controller, Instant AP, Aruba Central, gateways)

Which benefit does an ArubaOS 8 Mobility Controller cluster provide?

  1. Automatic conversion of Campus APs into Instant APs
  2. A shared IP address for Aruba Activate provisioning
  3. Replacement of the Mobility Master management plane
  4. Hitless failover with synchronized client state between cluster members Correct answer.

Explanation

Controllers in a cluster synchronize client state so that another member can take over with minimal disruption. This supports hitless failover for connected clients.

Question 22Aruba wireless architecture and product portfolio (Mobility Master/Mobility Controller, Instant AP, Aruba Central, gateways)

What does the ArubaOS 8 MultiZone feature allow?

  1. One AP to terminate CAP tunnels for multiple controllers simultaneously
  2. One Mobility Master to manage only a single controller
  3. One controller serving multiple independent zones with separate policies Correct answer.
  4. One client to authenticate against multiple ClearPass servers at once

Explanation

MultiZone partitions a single controller into multiple logical zones. Each zone can have its own APs, clients, and policies while sharing the hardware.

Question 23Aruba wireless architecture and product portfolio (Mobility Master/Mobility Controller, Instant AP, Aruba Central, gateways)

Which role is the Aruba 9000 series gateway primarily designed for?

  1. Headend or data-center VPN concentration and security Correct answer.
  2. Wireless client termination as a Mobility Controller replacement
  3. Branch office WAN aggregation with small port counts
  4. Cloud management of Instant APs

Explanation

The 9000 series targets headend and data-center deployments that require high VPN concentration and security throughput. Branch sites are typically served by the 7000 series.

Question 24Aruba wireless architecture and product portfolio (Mobility Master/Mobility Controller, Instant AP, Aruba Central, gateways)

Which statement about the Mobility Master's role in the data path is correct?

  1. It acts as the default gateway for every wireless client on the network
  2. It terminates CAP tunnels and encrypts client sessions
  3. It forwards all client traffic through a centralized tunnel
  4. It does not forward client traffic; controllers do the data plane Correct answer.

Explanation

The Mobility Master is a management-plane component and is not inserted into the client data path. Client traffic is handled by Mobility Controllers or gateways.

Question 25Aruba wireless architecture and product portfolio (Mobility Master/Mobility Controller, Instant AP, Aruba Central, gateways)

What happens in an Aruba Instant cluster if the virtual controller AP fails?

  1. All APs reboot and lose their configuration
  2. A new virtual controller is elected from the remaining APs Correct answer.
  3. The Mobility Master automatically takes over the VC role
  4. The cluster stops serving clients until a controller is added

Explanation

Instant APs elect a new virtual controller from the surviving cluster members when the current one is lost. Cluster configuration is replicated so service can continue.

Question 26Aruba wireless architecture and product portfolio (Mobility Master/Mobility Controller, Instant AP, Aruba Central, gateways)

Which operating system does Aruba position as its cloud-native platform for access points managed through Aruba Central?

  1. ArubaOS-Switch
  2. ArubaOS-CX
  3. ArubaOS 10 Correct answer.
  4. ArubaOS 8

Explanation

ArubaOS 10 is the cloud-native access point operating system built for management through Aruba Central, with configuration and telemetry handled in the cloud rather than on a local controller. ArubaOS 8 remains the operating system used by Mobility Controllers and gateways, so it is not the cloud-native AP platform.

Question 27Aruba wireless architecture and product portfolio (Mobility Master/Mobility Controller, Instant AP, Aruba Central, gateways)

A teleworker needs the corporate SSID at home, delivered over an IPsec tunnel to the campus controller while still using the home router for Internet access. Which Aruba AP operating mode is designed for this?

  1. Remote AP Correct answer.
  2. Campus AP
  3. Instant AP
  4. Mesh point

Explanation

Remote AP mode is intended for off-site locations such as home offices: the AP builds an IPsec tunnel to a controller or gateway and can forward corporate traffic through it. Campus AP mode assumes a local, trusted connection to a controller on the enterprise network, which does not fit a home Internet link.

Question 28Aruba wireless architecture and product portfolio (Mobility Master/Mobility Controller, Instant AP, Aruba Central, gateways)

An ArubaOS 8 design team wants RF channel and power plans computed centrally and refreshed automatically, rather than each radio deciding on its own. Which feature provides this?

  1. ARM
  2. AirMatch Correct answer.
  3. ClientMatch
  4. AppRF

Explanation

AirMatch performs RF planning in a centralized way, calculating channel and power assignments and distributing the resulting plan to the APs on a scheduled basis. ClientMatch instead deals with client steering, and AppRF deals with application visibility and policy, so neither produces the RF plan.

Question 29Aruba wireless architecture and product portfolio (Mobility Master/Mobility Controller, Instant AP, Aruba Central, gateways)

Which Aruba solution is aimed at small branch and home offices by combining Aruba Central management with a gateway that supplies local routing, VPN termination, and WLAN services?

  1. Dynamic Segmentation
  2. MultiZone
  3. Aruba Microbranch Correct answer.
  4. Aruba Clarity

Explanation

Aruba Microbranch targets small sites by pairing Aruba Central with a compact gateway, such as the 9000 series, that provides local network services and WLAN connectivity without a full campus controller. It is a distinct solution from the controller-side and policy features listed in the other options.

Question 30Aruba wireless architecture and product portfolio (Mobility Master/Mobility Controller, Instant AP, Aruba Central, gateways)

A hospital wants the same role-based firewall policy applied to wireless users and to wired users on Aruba access switches, with both traffic types tunneled to Aruba gateways. Which Aruba capability delivers this?

  1. Aruba ClientMatch
  2. Aruba MultiZone
  3. Aruba AirMatch
  4. Aruba Dynamic Segmentation Correct answer.

Explanation

Dynamic Segmentation applies role-based policies consistently by tunneling traffic from APs and Aruba switches to a controller or gateway, where the user role determines the enforcement applied. This lets wired and wireless clients share one policy model rather than relying on per-port VLAN design alone.

Question 31802.11 standards, WLAN RF fundamentals, and channel planning

Which frequency band is used by the 802.11a amendment?

  1. 5 GHz Correct answer.
  2. 6 GHz
  3. 2.4 GHz
  4. 60 GHz

Explanation

802.11a was ratified to operate in the 5 GHz UNII bands and uses OFDM with data rates up to 54 Mbps. It does not use the 2.4 GHz ISM band, which is the home of 802.11b and 802.11g. The 6 GHz and 60 GHz bands are associated with later amendments, not 802.11a.

Question 32802.11 standards, WLAN RF fundamentals, and channel planning

What is the maximum PHY data rate defined by the original 802.11b amendment?

  1. 54 Mbps
  2. 11 Mbps Correct answer.
  3. 5.5 Mbps
  4. 2 Mbps

Explanation

802.11b operates in 2.4 GHz with DSSS/CCK and defines rates of 1, 2, 5.5, and 11 Mbps. Its top rate is 11 Mbps. The 54 Mbps rate belongs to 802.11a/g, while 600 Mbps is an 802.11n theoretical rate.

Question 33802.11 standards, WLAN RF fundamentals, and channel planning

Which set of 2.4 GHz channels is conventionally used as the three non-overlapping 20 MHz channels in North America?

  1. 1, 6, and 11 Correct answer.
  2. 2, 7, and 12
  3. 1, 5, and 9
  4. 3, 8, and 13

Explanation

In the North American 2.4 GHz plan, channels 1, 6, and 11 are spaced five channels apart, so their 20 MHz spectral masks do not overlap. Other combinations may be used in some regulatory domains, but 1/6/11 is the standard three-channel reuse set. Channels such as 1/5/9 overlap and cause adjacent-channel interference.

Question 34802.11 standards, WLAN RF fundamentals, and channel planning

The unit dBm expresses power relative to which reference?

  1. 1 milliwatt Correct answer.
  2. An isotropic radiator
  3. 1 microwatt
  4. 1 watt

Explanation

dBm is an absolute power unit referenced to 1 milliwatt, so 0 dBm equals 1 mW and 20 dBm equals 100 mW. dBW uses 1 watt as its reference, and dBi refers to an isotropic radiator. Mixing these references is a common source of link-budget errors.

Question 35802.11 standards, WLAN RF fundamentals, and channel planning

A client reports a received signal level of -65 dBm and a noise floor of -95 dBm. What is the SNR?

  1. 160 dB
  2. 20 dB
  3. 25 dB
  4. 30 dB Correct answer.

Explanation

SNR is the difference in dB between signal and noise: -65 dBm minus -95 dBm equals 30 dB. In dB arithmetic, subtraction corresponds to a ratio, not to adding the two absolute levels. A 30 dB SNR is generally sufficient for high-throughput modulation.

Question 36802.11 standards, WLAN RF fundamentals, and channel planning

Which technology was introduced by 802.11n to increase throughput by using multiple antennas?

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

Explanation

802.11n introduced MIMO, using multiple transmit and receive antennas for spatial multiplexing and beamforming. OFDMA and BSS coloring are features of 802.11ax, while downlink MU-MIMO became prominent with 802.11ac. MIMO can raise throughput without increasing channel width.

Question 37802.11 standards, WLAN RF fundamentals, and channel planning

Which band does 802.11ac use for its standard operation?

  1. 2.4 GHz only
  2. 5 GHz only Correct answer.
  3. Both 2.4 GHz and 5 GHz
  4. 6 GHz only

Explanation

802.11ac is defined as a 5 GHz technology, using wider channels and higher-order modulation than 802.11n. It does not operate in 2.4 GHz; dual-band APs support 2.4 GHz clients through a separate 802.11n radio. The 6 GHz band is used by Wi-Fi 6E, not by 802.11ac.

Question 38802.11 standards, WLAN RF fundamentals, and channel planning

What is a major consequence of using a 40 MHz channel in the 2.4 GHz band?

  1. It completely eliminates co-channel interference
  2. It uses more spectrum and raises overlap risk Correct answer.
  3. It prevents all adjacent-channel overlap
  4. It creates additional non-overlapping channels

Explanation

A 40 MHz channel occupies two 20 MHz channels, but the 2.4 GHz band is only about 83 MHz wide. As a result, fewer non-overlapping channels remain and the chance of overlapping with neighboring APs rises. 40 MHz is therefore usually reserved for 5 GHz or clean 2.4 GHz environments.

Question 39802.11 standards, WLAN RF fundamentals, and channel planning

Which 802.11 feature divides a channel into subcarriers assigned to different clients for simultaneous uplink and downlink transmissions?

  1. 256-QAM
  2. OFDMA Correct answer.
  3. 80 MHz channel bonding
  4. DSSS

Explanation

802.11ax introduces OFDMA, which partitions the channel into resource units that can serve multiple clients at the same time. This improves efficiency for many small packets rather than only raising peak rate. 256-QAM is a modulation order, DSSS is an older spread-spectrum technique, and channel bonding widens the channel.

Question 40802.11 standards, WLAN RF fundamentals, and channel planning

Which 5 GHz UNII band requires DFS because it shares spectrum with radar systems?

  1. UNII-2A Correct answer.
  2. UNII-3
  3. The 2.4 GHz ISM band
  4. UNII-1

Explanation

UNII-2A (5250–5350 MHz) and UNII-2C (5470–5725 MHz) are DFS bands in many regulatory domains because weather and military radar operate there. UNII-1 and UNII-3 generally do not require DFS. The 2.4 GHz ISM band is not a 5 GHz UNII band.

Question 41802.11 standards, WLAN RF fundamentals, and channel planning

An AP transmits at 17 dBm, the antenna has 6 dBi gain, and the cable loss is 2 dB. What is the EIRP?

  1. 23 dBm
  2. 19 dBm
  3. 25 dBm
  4. 21 dBm Correct answer.

Explanation

EIRP is calculated as transmit power plus antenna gain minus cable loss: 17 + 6 - 2 = 21 dBm. Gains and losses are combined by addition and subtraction in the logarithmic dB domain. This yields the equivalent isotropic radiated power used for regulatory comparisons.

Question 42802.11 standards, WLAN RF fundamentals, and channel planning

For a fixed distance in free space, doubling the frequency increases free-space path loss by approximately how much?

  1. 10 dB
  2. 3 dB
  3. 20 dB
  4. 6 dB Correct answer.

Explanation

Free-space path loss is proportional to 20 log10(frequency), so doubling frequency adds 20 log10(2), about 6 dB. This explains why 5 GHz signals suffer more path loss than 2.4 GHz signals at the same distance. The effect is separate from material penetration and antenna gain.

Question 43802.11 standards, WLAN RF fundamentals, and channel planning

Which clearance percentage is the commonly recommended minimum for the first Fresnel zone in a point-to-point link?

  1. 40 percent
  2. 60 percent Correct answer.
  3. 80 percent
  4. 20 percent

Explanation

Best practice is to keep at least 60 percent of the first Fresnel zone unobstructed, because partial blockage can cause diffraction and signal loss. Full 100 percent clearance is ideal but often impractical. The first Fresnel zone is widest at the midpoint of the link.

Question 44802.11 standards, WLAN RF fundamentals, and channel planning

Two APs are configured on channel 6 and have overlapping coverage. What type of interference is this?

  1. Fresnel interference
  2. Co-channel interference Correct answer.
  3. Intermodulation interference
  4. Adjacent-channel interference

Explanation

Co-channel interference occurs when multiple radios use the same channel in the same coverage area, forcing contention and reducing airtime. Adjacent-channel interference instead comes from energy leaking from a nearby but different channel. Proper channel reuse and power control reduce co-channel interference.

Question 45802.11 standards, WLAN RF fundamentals, and channel planning

What is the typical effect of reducing an AP's transmit power in a dense WLAN?

  1. It enlarges the cell and increases co-channel interference
  2. It increases the AP's maximum data rate
  3. It disables DFS operation
  4. It shrinks the cell and can reduce co-channel interference Correct answer.

Explanation

Lower transmit power shrinks the coverage footprint, which can limit how far a client hears the AP and reduce overlap between cells. Less overlap allows more frequent channel reuse and lowers co-channel interference. Power changes do not directly raise the PHY rate or affect DFS.

Question 46802.11 standards, WLAN RF fundamentals, and channel planning

Which mechanism helps mitigate the hidden-node problem in an 802.11 WLAN?

  1. RTS/CTS exchange Correct answer.
  2. ACK frames
  3. Probe requests
  4. Beacon frames

Explanation

A hidden node cannot hear another station's transmission but can hear the AP, so carrier sense fails. RTS/CTS reserves the medium through the AP and tells other stations to defer, reducing collisions from hidden nodes. Beacons, ACKs, and probes do not provide this reservation function.

Question 47802.11 standards, WLAN RF fundamentals, and channel planning

How does spatial multiplexing increase WLAN throughput?

  1. By reducing the guard interval to zero
  2. By widening the channel from 20 MHz to 160 MHz
  3. By sending multiple independent data streams Correct answer.
  4. By using a single spatial stream at a much higher transmit power

Explanation

Spatial multiplexing transmits different data streams on the same frequency at the same time, relying on multipath and multiple antennas to separate them. Throughput scales with the number of usable spatial streams, up to the AP and client capabilities. It does not require wider channels or zero guard interval.

Question 48802.11 standards, WLAN RF fundamentals, and channel planning

How many 20 MHz channels are combined to form an 80 MHz WLAN channel?

  1. Eight
  2. Three
  3. Two
  4. Four Correct answer.

Explanation

Channel width in 802.11 is built from 20 MHz blocks, so 80 MHz equals four adjacent 20 MHz channels. 40 MHz uses two blocks and 160 MHz uses eight. Wider channels raise peak throughput but consume more spectrum and reduce the number of available channels.

Question 49802.11 standards, WLAN RF fundamentals, and channel planning

What determines the allowed 5 GHz channels and maximum EIRP for an AP?

  1. The configured channel width only
  2. The AP's regulatory domain Correct answer.
  3. The AP's SSID
  4. The client's RSSI

Explanation

Regulatory domains encode country-specific rules for which frequencies may be used and at what maximum EIRP. An AP must be set to the correct domain so it does not transmit outside local law. SSID, RSSI, and channel width do not define legal channel availability.

Question 50802.11 standards, WLAN RF fundamentals, and channel planning

A signal measured at -50 dBm is how much stronger than a signal measured at -70 dBm?

  1. 120 dB
  2. 10 dB
  3. 30 dB
  4. 20 dB Correct answer.

Explanation

The difference is -50 minus -70, which equals 20 dB. Because dBm is logarithmic, a 20 dB difference means the -50 dBm signal has 100 times the power of the -70 dBm signal. Adding the magnitudes would incorrectly give 120.