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In the 2.4 GHz band, only channels 1, 6, and 11 are non-overlapping, meaning that they do not share any frequency spectrum with each other. This makes them the preferred channels for Wi-Fi networks to minimize interference with other devices that use the same band, such as Bluetooth, microwave ovens, cordless phones, etc. Using non-overlapping channels also allows for better performance and throughput, as devices on the same channel have to contend for the medium and avoid collisions. Channels 2 to 5 overlap with channel 1, channels 7 to 10 overlap with channel 6, and channels 12 and 13 overlap with channel 11. Channel 14 is not allowed in most countries and regions, and it also overlaps with channel 11. Therefore, using any of these channels would cause interference with the non-overlapping channels and degrade the network quality. The 2.4 GHz band has a total of 14 channels, each with a bandwidth of 22 MHz and a center frequency separated by 5 MHz. However, the actual frequency range used by each channel is wider than 22 MHz, as the signal spreads out due to modulation. This means that adjacent channels partially overlap with each other, and only channels that are 25 MHz apart or more are completely non-overlapping. The following table shows the center frequency and frequency range of each channel in the 2.4 GHz band:

Table

Channel

Center frequency (MHz)

Frequency range (MHz)

1

2412

2401-2423

2

2417

2406-2428

3

2422

2411-2433

4

2427

2416-2438

5

2432

2421-2443

6

2437

2426-2448

7

2442

2431-2453

8

2447

2436-2458

9

2452

2441-2463

10

2457

2446-2468

11

2462

2451-2473

12

2467

2456-2478

13

2472

2461-2483

14

2484

2473-2495

As shown in the table, only channels 1, 6, and 11 have a 25 MHz separation between their center frequencies, and therefore do not overlap with each other or any other channel. This makes them the best choice for Wi-Fi communications in the 2.4 GHz band. References:

Aruba Certified Network Technician (ACNT) | HPE Aruba Networking

Aruba Documentation Portal

List of WLAN channels - Wikipedia

Why Channels 1, 6 and 11? | MetaGeek

All about WiFi Channels & Frequency Bands – A simple Guide

WiFi Channels: Complete Guide with Tips to Boost Signal Performance

Radio frequency (RF) power is the amount of energy radiated by an antenna or a transmitter in the form of electromagnetic waves. RF power can be measured in different units, such as watts (W), milliwatts (mW), or decibels (dB). However, some units are more convenient than others for expressing RF power due to its logarithmic nature1

Logarithmic units, such as dB, are useful for comparing power levels that span several orders of magnitude, such as the power output of a radio station versus the power received by a mobile device. Logarithmic units also simplify the calculation of power ratios, gains, and losses, as they can be added or subtracted instead of multiplied or divided12

One common logarithmic unit for RF power is the decibel relative to milliwatt (dBm), which is defined as the power level in dB with reference to 1 mW. For example, 0 dBm means 1 mW, 10 dBm means 10 mW, 20 dBm means 100 mW, and so on. Conversely, -10 dBm means 0.1 mW, -20 dBm means 0.01 mW, and so on. The dBm unit is convenient because many RF signals, especially in wireless communication, are at fairly low power levels, and the dBm unit can express them in a short form23

Another logarithmic unit for RF power is the decibel relative to isotrope (dBi), which is defined as the power level in dB with reference to an isotropic radiator, which is a hypothetical antenna that radiates equally in all directions. The dBi unit is used to measure the gain of an antenna, which is the ratio of the power radiated by the antenna in a specific direction to the power radiated by an isotropic radiator. For example, a 3 dBi antenna means that it radiates 3 dB more power than an isotropic radiator in its main direction. The dBi unit is not suitable for expressing absolute power levels, as it depends on the reference antenna45

Therefore, the recommended unit of measurement for expressing RF power due to its logarithmic nature is the dBm, as it is an absolute unit that can compare power levels across a wide range and simplify power calculations. The dBi unit is only used for expressing antenna gain, which is a relative unit that depends on the reference antenna. The other units, such as lumens and milliwatts, are not logarithmic and are not commonly used for RF power measurement12345 References: 1: Radio frequency - Wikipedia 2: dBm - Wikipedia 3: RF power measurement, Part 1: Why and where - Analog IC Tips 4: Radiant intensity - Wikipedia 5: Fundamentals of RF and Microwave Power Measurements - UC Davis

The subnet mask 255.255.252.0 is equivalent to the CIDR notation /22, which means that 22 bits are used for the network prefix and 10 bits are used for the host part. To calculate the number of addresses that this subnet mask provides, we can use the formula2n−2, wherenis the number of bits in the host part. In this case,n=10, so the number of addresses is210−2=1024−2=1022. The subtraction of 2 is because the first and the last addresses are reserved for the network identifier and the broadcast address, respectively. Therefore, the subnet mask 255.255.252.0 provides 1022 usable addresses for hosts, plus 2 reserved addresses, for a total of 1024 addresses.References:IP Subnet Calculator,How many host addresses are available on the network … - ITExamAnswers

A BSSID is a 48-bit label that identifies a basic service set (BSS) within a wireless network. A BSS is a subgroup of devices that share physical-layer medium access characteristics, such as radio frequency, modulation scheme, and security settings. A BSSID is usually the MAC address of the access point (AP) that creates the BSS, or a randomly generated value in an ad hoc network. A BSSID is different from an SSID, which is the name of the wireless network that users see and connect to. An SSID can have multiple BSSIDs associated with it, depending on the number and location of the APs. A BSSID is used to differentiate between different BSSs and to facilitate roaming and load balancing among them. References: https://internetspeedtest.world/wiki/bssid

https://www.minthaik.com/bssid-basic-service-set-identifier/

 Aruba Central is a cloud-based networking solution that offers simplicity, security, and scalability for managing Aruba network infrastructure. It uses HTTPs to communicate with networking equipment such as wireless, wired, VPN, and SD-WAN devices. It also provides AI-powered insights, workflow automation, and advanced security features to unifyoperations across campus, branch, data center, and remote work environments. Aruba Central does not require an on-premises server, nor does it use SNMP for management. It also does not support third-party networking equipment, as it is designed for Aruba ESP (Edge Services Platform). References: Aruba Central for Cloud-managed networking, About Aruba Central, Aruba Central data sheet

The end command is used to exit from any configuration context and return to the manager context. The manager context is indicated by the # symbol at the end of the prompt. The manager context allows you to execute commands that do not require saving changes to the configuration, such as show or clear commands. The disable command is used to exit from the manager context and return to the operator context, which is indicated by the > symbol. The quit and exit commands are used to exit from the current context and return to the parent context, such as from config-if to config. However, these commands do not move you directly to the manager context from any configuration context. Therefore, the correct answer is A. end. References: Navigating to the manager context (#) - Aruba, Manager context (#) - Aruba

 The 5 GHz band is a radio frequency band used for Wi-Fi communications. It has a higherdata bandwidth than the 2.4 GHz band, but a shorter range and less penetration through walls. The 5 GHz band is divided into several sub-bands, each with a different set of channels. One of these sub-bands is the U-NII-3 band, which covers the frequency range from 5725 MHz to 5850 MHz. This sub-band contains 24 non-overlapping channels, numbered from 149 to 172. Channels 149 to 161 are part of the 5 GHz band and can be used for Wi-Fi communications. Channels 165 and 169 are restricted to indoor use only, and channel 173 is not allowed in some regions. Channels 12, 13, and 14 are not part of the 5 GHz band, but belong to the 2.4 GHz band, which has a different set of channels and regulations. U-NII-5 is not a valid sub-band name, but a proposed extension of the 5 GHz band to include the frequency range from 5925 MHz to 7125 MHz. This extension is not yet approved or implemented, and therefore not part of the 5 GHz band. References: List of WLAN channels, What’s the Difference Between 2.4 and 5 GHz Wi-Fi (and Which Should I Use)?, What is the difference between 2.4 GHz, 5 GHz, and 6 GHz wireless frequencies?

The OSI model is a conceptual framework that describes the process of transmitting data between computers. It is divided into seven layers, each with a specific function. The application layer, or layer 7, is the highest layer of the OSI model and is responsible for creating data. The application layer provides services such as resource sharing, remote file access, email, web browsing, etc. The data created by the application layer is then passed down to the presentation layer, which translates it into a common format for the lower layers. The data is then further processed by the session, transport, network, data link, and physical layers until it reaches the destination12 References:

What is OSI Model | 7 Layers Explained

OSI model - Wikipedia

An access point is a device that creates a wireless local area network (WLAN) by connecting wireless devices to a wired network. An access point performs two main functions: bridging and wireless connectivity.

Bridging is the process of forwarding data frames between different networks or network segments. An access point bridges wireless frames from wireless devices to the wired network, and vice versa, using the destination MAC address of the frame. This allows wireless devices to communicate with other devices on the same network or on different networks.

Wireless connectivity is the process of providing a wireless signal to wireless devices, such as laptops, smartphones, tablets, etc. An access point offers wireless connectivity to endpoints by broadcasting a service set identifier (SSID), which is the name of the wireless network. Wireless devices can scan for available SSIDs and connect to the access point by providing the correct security credentials, such as a password or a certificate.

The other statements are false because:

A. They use destination IP addresses to switch the packets. This is false because access points do not use IP addresses to switch packets. IP addresses are used at layer three of the OSI model, which is the network layer. Access points operate at layer two of the OSI model, which is the data link layer. Access points use MAC addresses to switch frames, not packets.

C. They are used to interconnect wireless devices only. This is false because access points are not used to interconnect wireless devices only. Access points are also used to connect wireless devices to a wired network, which may contain other devices, such as routers, switches, servers, etc.

E. They only operate at Layer three of the OSI model. This is false because access points do not operate at layer three of the OSI model, which is the network layer. Access points operate at layer two of the OSI model, which is the data link layer. Access points do not use network layer protocols, such as IP, to perform their functions. References:

What is an Access Point? - Cisco

Access Point | What is it and how it works?IAPP specification

A hardwire desktop PC belongs to the category of stationary devices, which are devices that are fixed in one location and do not move. Stationary devices typically have a constant power supply and a wired network connection. Examples of stationary devices are desktop PCs, servers, printers, and IP phones. Stationary devices are different from mobile devices, which are devices that can move from one location to another and connect to the network wirelessly. Mobile devices can be further classified into somewhat mobile devices, highly mobile devices, and intermittent mobile devices, depending on their mobility patterns and network requirements. Examples of mobile devices are laptops, tablets, smartphones, and wearable devices. References:

Aruba Certified Network Technician (ACNT) | HPE Aruba Networking

Aruba Documentation Portal