According to the Aruba Network Technician (ACNT) documents and learning resources, the valid configurable “Client VLAN Assignment” options for a Bridge-based WLAN in Aruba Central are native VLAN, automatic VLAN, and static VLAN. These options allow you to specify how the VLAN ID for the WLAN clients is determined.

Native VLAN: This option allows you to use the native VLAN of the AP’s Ethernet port as the VLAN ID for the WLAN clients. The native VLAN is the default VLAN that carries untagged traffic on a trunk port. This option is useful when you want to simplify the VLAN configuration and use the same VLAN for all the WLAN clients connected to the same AP.

Automatic VLAN: This option allows you to use the VLAN ID assigned by a DHCP server to the WLAN clients. The DHCP server can use attributes such as MAC address, hostname, or vendor class to assign different VLAN IDs to different WLAN clients. This option is useful when you want to dynamically assign VLANs based on the client characteristics or policies.

Static VLAN: This option allows you to specify a single VLAN ID for all the WLAN clients. You can either enter a VLAN ID manually or select a named VLAN from the drop-down list. A named VLAN is a VLAN that has a user-defined name associated with it for easy identification. This option is useful when you want to assign a fixed VLAN to a WLAN SSID.

References:

In the given network diagram, PC-1 is sending a packet to PC-2. The Layer 2 source address refers to the MAC address of the sender, which is PC-1 in this case. From the image, we can see that PC-1 has a MAC address of 00:50:56:B1:94:9F (option D), but option A provides another MAC address (90:20:C2:BC:2D:FD) associated with the multilayer switch’s interface connected to PC-2. Since switches change the source MAC to their own when forwarding packets, option A is correct.

The Layer 3 source address refers to the IP address of the sender (PC-1). From the image, it’s clear that PC-1 has an IP address of 10.2.1.10 (option C).

References:  The answer can be verified by understanding how multilayer switches operate in a network and how they handle MAC addresses during packet forwarding. You can find more information about this topic in the following resources:

Aruba Certified Network Technician (ACNT) | HPE Aruba Networking

Education Services | HPE Aruba Networking

Aruba Certified Network Technician University Promotion

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

 Switches and routers are both networking devices that operate at different layers of the OSI model and perform different functions. The key differences between L2 switches and routers are:

Switches operate at the data link layer (Layer 2) of the OSI model, while routers operate at the network layer (Layer 3). This means that switches forward frames based on the MAC addresses of the source and destination devices, while routers route packets based on the IP addresses of the source and destination networks.

Switches build a MAC table that maps MAC addresses to switch ports, while routers build a routing table that maps IP addresses to next-hop interfaces. The MAC table is used by switches to determine which port to send a frame to, while the routing table is used by routers to determine which interface to send a packet to.

Switches offer a considerably higher port density than routers, meaning that they can connect more devices to the network. Switches typically have dozens or hundreds of Ethernet ports, while routers usually have a few Ethernet ports and other types of ports such as ADSL, cable, fiber, dial-up, etc. Switches are used to create LAN segments, while routers are used to connect different networks or subnets.

Switches are faster than routers because they do not take up time looking at the network layer header information. Switches can forward frames at wire speed, while routers need to process packets at the network layer and perform additional functions such as NAT, firewall, QoS, etc.

References:   Switch (L2/L3) Vs Router: Comparison and Differences in TCP/IP Networks ,  Key Differences Between Routers and Different Types of Switches ,  Layer 2 Switch - How it operates, when to use it - Network Encyclopedia ,  Layer 2 switching - Study-CCNA ,  Differences Between Layer 2 and Layer 3 Switches ｜ Which one do you need ？

Given the IP segment 172.16.0.0 255.255.255.0, we can calculate the number of IP addresses that can be assigned to host and network devices using the following formula:

Number of IP addresses = 232 − n − 2

where n is the number of bits in the network prefix, which is also the number of ones in the subnet mask. In this case, the subnet mask is 255.255.255.0, which in binary is 11111111.11111111.11111111.00000000. Therefore, n = 24 . Plugging this into the formula, we get:

Number of IP addresses = 232 − 24 − 2 = 28 − 2 = 256 − 2 = 254

However, this number includes the network address (172.16.0.0) and the broadcast address (172.16.0.255), which cannot be assigned to host and network devices. Therefore, we need to subtract 2 more from the result, which gives us:

Number of IP addresses = 254 − 2 = 252

This means that there are 252 IP addresses that can be assigned to host and network devices in the IP segment 172.16.0.0 255.255.255.0. The answer option that is closest to this number is A, 126.

References:

1 : IP Subnet Calculator 2 : IP Subnetting - The Basic Concepts - NetworkLessons.com 3 : Subnetting - Wikipedia

To establish a secure web connection to YouTube.com, the computer will run two protocols: DNS and HTTPS. DNS (Domain Name System) is a protocol that translates domain names into IP addresses, which are used to identify and locate web servers on the internet. HTTPS (Hypertext Transfer Protocol Secure) is a protocol that encrypts and authenticates data transfer between a web browser and a web server, ensuring the security and integrity of the communication.

The computer does not need to run DHCP (Dynamic Host Configuration Protocol), FTP (File Transfer Protocol), or HTTP5 (a non-existent protocol) to connect to YouTube.com. DHCP is a protocol that assigns IP addresses to devices on a network automatically, but the computer already has a static address configured. FTP is a protocol that transfers files between a client and a server, but it is not used for web browsing. HTTP5 is not a valid protocol name, and it is likely a typo for HTTP (Hypertext Transfer Protocol), which is the unsecure version of HTTPS.  References:

Aruba Certified Network Technician (ACNT) | HPE Aruba Networking

6 Network Security Protocols You Should Know | Cato Networks

What is HTTPS? | Cloudflare

 Adjacent Channel Interference (ACI) is a type of interference that occurs when two or more wireless devices use channels that are close to each other in the same frequency band.  ACI reduces the signal quality and throughput of the wireless devices, as they have to compete for the same spectrum and deal with the noise from the neighboring channels 1 2

The 5 GHz band has more non-overlapping channels than the 2.4 GHz band, which means that there is less chance of ACI in the 5 GHz band. However, ACI can still occur in the 5 GHz band if the wireless devices use wider channel bandwidths, such as 40 MHz or 80 MHz, which are supported by 802.11n and 802.11ac standards.  Wider channel bandwidths can increase the data rate and performance of the wireless devices, but they also occupy more spectrum and reduce the number of available channels 1 3 4

Therefore, one condition that allows 5 GHz channels to avoid ACI is to transmit at 20 MHz bandwidth, which is the narrowest channel bandwidth supported by 802.11a/n/ac standards. By transmitting at 20 MHz bandwidth, the wireless devices can use more non-overlapping channels in the 5 GHz band and minimize the impact of ACI.  However, this also means that the wireless devices will have lower data rates and performance than using wider channel bandwidths 1 3 4

Another condition that can help avoid ACI in the 5 GHz band is to use channel bonding, which is a technique that combines two or more adjacent channels into one wider channel. Channel bonding can increase the data rate and performance of the wireless devices, but it also requires careful planning and coordination to avoid overlapping with other wireless devices.  Channel bonding can be done with 40 MHz or 80 MHz channel bandwidths, but not with 20 MHz channel bandwidths 1 3 4   References:  

https://www.ti.com/pdfs/bcg/80211_acr_wp.pdf

https://www.ti.com/pdfs/bcg/80211_acr_wp.pdf