HPE3-U01 Aruba Certified Network Technician Exam (ACNT) Questions and Answers

To convert a binary number to a decimal number, we need to follow these steps:

• Write down the binary number and assign a power of 2 to each digit, starting from the rightmost with 2^0.
• Convert each binary digit to its decimal equivalent by multiplying it with its power of 2.
• Add all the decimal values to get the decimal equivalent of the binary number.

Let’s apply these steps to the binary number 10001010:

• 10001010 = 0 × 2^0 + 1 × 2^1 + 0 × 2^2 + 1 × 2^3 + 0 × 2^4 + 0 × 2^5 + 0 × 2^6 + 1 × 2^7
• 10001010 = 0 + 2 + 0 + 8 + 0 + 0 + 0 + 128
• 10001010 = 138 in decimal

Therefore, the decimal equivalent of the binary number 10001010 is 138 (option A).

References: The answer can be verified by using the following resources:

• Convert 10001010 from binary to decimal - Calculator Online
• How to Convert decimal number 10001010 in binary? - CoolConversion
• 10001010 to decimal - Calculatio
• Binary Code | Binary: 10001010 | Decimal: 138 | Bits: 8

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 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

A collision occurs when two or more devices try to transmit data at the same time on a shared medium, such as a bus or a hub. Collisions degrade network performance and cause data loss. Switches mitigate collisions by creating separate collision domains for each port. This means that each port can transmit and receive data without interfering with other ports. Switches also use full-duplex communication, which allows simultaneous transmission and reception of data on each port, further reducing the chances of collisions. VLANs and L3 protocols do not affect collisions, as they operate at different layers of the network model. Proprietary features are not a general characteristic of switches, and may not be compatible with other vendors’ switches. References: Aruba Certified Network Technician (ACNT) | HPE Aruba Networking, Aruba Documentation Portal

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

 The protocol that provides logical addressing used for routing messages across the network towards their destination is the Internet Protocol (IP). IP is a network layer protocol that assigns a unique numerical identifier to each device on a network, called an IP address. IP addresses are used to identify the source and destination of data packets, and to determine the best path to deliver them. IP is a connectionless and best-effort protocol, meaning that it does not guarantee the delivery, order, or integrity of the packets. IP relies on other protocols, such as TCP, to provide reliable and orderly data transfer.

The other options are incorrect because:

B. Transmission Control Protocol (TCP) is a transport layer protocol that provides reliable and orderly data delivery by establishing a connection between devices and providing error-checking and retransmission mechanisms. TCP does not provide logical addressing or routing functions, but it uses IP addresses to identify the endpoints of a connection.

C. Wired Ethernet is a data link layer protocol that defines the physical and logical characteristics of a wired network, such as cable types, frame formats, and MAC addresses. MAC addresses are used to identify the physical devices on a network segment, but they are not used for routing messages across the network. Ethernet does not provide logical addressing or routing functions, but it relies on IP to do so.

D. Link Layer Discovery Protocol (LLDP) is a data link layer protocol that allows devices to discover and advertise information about themselves and their neighbors on a network, such as device type, capabilities, port configuration, and VLAN membership. LLDP does not provide logical addressing or routing functions, but it can help network administrators to troubleshoot and optimize the network topology. References:

• Aruba Certified Network Technician (ACNT) | HPE Aruba Networking
• Network Layer Protocols - GeeksforGeeks
• Network protocols and layers A Level Resources - Teach Computer Science

 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?

The PCs are not able to successfully establish bidirectional communication because they are on different subnets and their default gateways are not configured correctly. The default gateway is the IP address of the router interface that connects to the same subnet as the PC. The default gateway allows the PC to send packets to destinations outside its own subnet. In this case, PC-1 and PC-2 are on the 172.16.30.0/24 and 172.16.31.0/24 subnets respectively, and the router interfaces are 172.16.30.254 and 172.16.31.254 respectively. Therefore, the correct default gateway for PC-1 is 172.16.30.254 and the correct default gateway for PC-2 is 172.16.31.254. Changing PC-2’s default gateway to 172.16.31.254 will enable the communication between PC-1 and PC-212 References:

• Aruba Certified Network Technician (ACNT) - HPE Certification and Learning
• Aruba Certified Network Technician (ACNT) - Aruba Networks.

The Wi-Fi Alliance is an organization that promotes interoperability among WLAN device manufacturers. The Wi-Fi Alliance is an important organization for the advancement of wireless LAN (WLAN) technology. It develops certification programs and technologies that deliver quality Wi-Fi experiences. Members have completed more than 80,000 certifications. Through industry-developed comprehensive testing, Wi-Fi Alliance certification programs ensure that Wi-Fi products from multiple manufacturers work well together. These certification programs are foundational to the rapid adoption and proliferation of Wi-Fi products in home, office, and public access locations around the world and underpin the success of Wi-Fi technology proliferation. Only Wi-Fi CERTIFIED™ products have been tested to deliver interoperability with the latest technologies, and industry-standard security protections. The Wi-Fi CERTIFIED logo gives consumersconfidence that the Wi-Fi devices purchased deliver a positive user experience, regardless of brand. For retailers, vendors, and service providers, the Wi-Fi CERTIFIED seal of approval means consistent performance and better user experience. A company must be a member of Wi-Fi Alliance ® and achieve certification to use the Wi-Fi CERTIFIED logo and Wi-Fi CERTIFIED certification marks. The Wi-Fi Alliance certification programs cover the following categories: Connectivity, Security, Mobility, Coexistence, and Performance123. References: Certification | Wi-Fi Alliance, Programs | Wi-Fi Alliance, Aruba Certified Network Technician Exam HPE3-U01 Actual Questions, Why Wi-Fi Certification Really Matters | Aruba Blogs

 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?

 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

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

To configure interfaces 1/1/1 and 1/1/2 as VLAN 10 access ports in ArubaOS-CX switches, the following commands are required:

switch(config)# vlan 10

switch(config-vlan-10)# name VLAN10

switch(config-vlan-10)# exit

switch(config)# interface 1/1/1

switch(config-if)# no shutdown

switch(config-if)# vlan access 10

switch(config-if)# exit

switch(config)# interface 1/1/2

switch(config-if)# no shutdown

switch(config-if)# vlan access 10

switch(config-if)# exit

Option B shows the correct syntax and sequence of commands to create VLAN 10, assign a name to it, and configure the interfaces as access ports in that VLAN. Option A is incorrect because it uses the wrong keyword vlan-id instead of vlan access. Option C is incorrect because it does not create VLAN 10 before assigning the interfaces to it. Option D is incorrect because it uses the wrong keyword vlan mode instead of vlan access. References: ArubaOS-CX 10.05 Fundamentals Guide 6200 Switch Series, Configuring VLANs on AOS-CX - Aruba

Ethernet is a protocol that provides frame delivery using physical addressing and error detection using frame check sequence. Ethernet frames have a source and destination MAC address that identify the physical devices on the network. Ethernet frames also have a frame check sequence (FCS) field that uses a cyclic redundancy check (CRC) to detect errors in the frame. If the receiver calculates a different FCS value than the one in the frame, it discards the frame and may request a retransmission. Link Layer DiscoveryProtocol (LLDP) is a protocol that allows devices to discover and advertise information about themselves and their neighbors. TCP/IP is a suite of protocols that operate at the network and transport layers, not the data link layer. User Datagram Protocol (UDP) is a transport layer protocol that provides connectionless and unreliable data delivery, without error detection or correction. References: Ethernet Frame Format - Aruba, Frame check sequence - Wikipedia

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