HP Updated HPE3-U01 Exam Questions and Answers by carys

 A switch is a device that operates at the data link layer (Layer 2) of the OSI model. It is responsible for forwarding frames based on the MAC addresses of the source and destination devices. A switch can also perform media access control, VLAN tagging, QoS, and other Layer 2 functions. A router, on the other hand, operates at the network layer (Layer 3) and routes packets based on their IP addresses. A transceiver is a device that converts electrical signals to optical signals and vice versa, and operates at the physical layer (Layer 1). A UTP cable is a type of twisted pair cable that is also used at the physical layer to transmit data. References: Data link layer - Wikipedia, Data Link Layer | Layer 2 | The OSI-Model, What is Layer 2? - Definition from Techopedia, An Overview of Layer 2 Ethernet – What is it and why does it matter?

 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 channels12

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 channels134

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 alsomeans that the wireless devices will have lower data rates and performance than using wider channel bandwidths134

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 bandwidths134 References: 

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

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

Role Based controls are a feature of Aruba Central that allows you to assign different access privileges and policies to different groups of users on a WLAN network. You can set the Role Based controls in the Security section of the Aruba Central WLAN configuration Wizard. In this section, you can configure the following parameters:

• Authentication Type: The method of verifying the identity of users who connect to the WLAN network. You can choose from several options, such as WPA2-Enterprise, WPA2-Personal, Captive Portal, MAC Authentication, or Open.
• Authentication Server: The server that performs the authentication process for the users. You can select an existing server from the list, or create a new one by clicking the + icon. You can also configure the server settings, such as IP address, port, shared secret, and timeout.
• User Role Assignment: The method of assigning user roles to the authenticated users. You can choose from several options, such as Default Role, Role Derivation, or Server Group Role. A user role is a set of firewall policies and VLAN settings that define the access privileges and restrictions for a group of users.
• Default User Role: The user role that is assigned to the users by default, if no other role assignment method is selected. You can select an existing user role from the list, or create a new one by clicking the + icon. You can also configure the user role settings, such as firewall policies, VLAN ID, and bandwidth limit.

References:

• Configuring Security Settings for Wireless Network
• Basic WLAN Configuration Workflow