HPE3-U01 Sample Questions Answers

The 051 Model is a reference model that describes how data communications occur on a network using five layers: physical, data link, network, transport, and application. The 051 Model is based on the OSI Model, which has seven layers, but it simplifies the presentation and session layers into the application layer. The 051 Model is used to understand the functions and interactions of different network components, such as devices, protocols, and services. Each layer of the 051 Model has a specific role and responsibility in the data communication process, as follows:

• The physical layer defines the electrical and mechanical characteristics of the transmission medium, such as cables, connectors, and signals. It also determines how data is encoded into bits and transmitted over the medium.
• The data link layer defines the rules and methods for accessing and sharing the transmission medium among multiple devices. It also provides error detection and correction mechanisms to ensure reliable data delivery.
• The network layer defines the logical addressing and routing schemes for data packets across different networks. It also provides congestion control and fragmentation/reassembly functions to optimize network performance.
• The transport layer defines the end-to-end communication and reliability services for data segments between applications. It also provides flow control and multiplexing/demultiplexing functions to manage data streams.
• The application layer defines the protocols and services that enable user applications to exchange data over the network. It also provides functions such as encryption, authentication, and compression to enhance data security and efficiency.

References:

• 051 Model
• OSI Model
• Network Fundamentals

To save the switch configuration changes, so they survive a switch reboot, you can use either the write memory or the save memory command. Both commands perform the same function, which is to copy the running configuration to the startup configuration. The running configuration is the current active configuration in the switch’s RAM, while the startup configuration is the configuration that is loaded when the switch boots up. By saving the configuration changes to the startup configuration, you ensure that they are preserved after a reboot12. The other commands are not valid for saving the configuration changes. The copy running-config checkpoint backup and copy running-config checkpoint startup-config commands are used to create checkpoints, which are snapshots of the running configuration that can be used to roll back changes in case of errors3. The store memory command does not exist in Aruba switches. References: 1: Saving Configuration Changes - Aruba 2: [ArubaOS-Switch 16.10 CLI Reference Guide] 3: [ArubaOS-Switch 16.10 Configuration and Management Guide] : https://www.arubanetworks.com/techdocs/ArubaOS-Switch_16.10/5200-6928.pdf : https://www.arubanetworks.com/techdocs/ArubaOS-Switch_16.10/5200-6929.pdf

 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?

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

DNS (Domain Name System) is the protocol that performs name to IP resolution. DNS is a hierarchical and distributed database that maps domain names to IP addresses and vice versa. DNS allows users to access network resources using human-readable names instead of numerical addresses. DNS also provides other information such as mail exchange servers, name servers, and text records. DNS operates on the application layer of the TCP/IP model and uses UDP port 53 for queries and responses. DNS consists of several components, such as resolvers, name servers, zones, and records. Resolvers are clients that send queries to name servers and receive responses. Name servers are servers that store and provide DNS information for a domain or a zone. Zones are logical partitions of the DNS namespace that are delegated to different name servers. Records are data entries that define the mapping between names and addresses or other attributes. References: https://www.geeksforgeeks.org/address-resolution-in-dns-domain-name-server/

https://networkencyclopedia.com/name-resolution/

https://www.ibm.com/docs/en/aix/7.2?topic=protocol-tcpip-name-resolution

 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 device that provides high ethernet port density for connecting wired clients is a switch. A switch is a device that operates at the data link layer (layer two) of the OSI model and forwards frames between devices on the same network based on their MAC addresses1. A switch can have multiple ports, ranging from 8 to 48 or more, that can connect to various wired devices, such as computers, IP phones, and printers2. A multilayer switch is a switch that can also operate at the network layer (layer three) of the OSI model and perform routing functions based on IP addresses3. Therefore, statements D and E are correct. Statements A, B, and C are incorrect because they describe devices that provide wireless connectivity, not wired connectivity. A wireless router is a device that combines the functions of a router and an access point and provides wireless access to the internet. A router is a device that operates at the network layer (layer three) of the OSI model and forwards packets between different networks based on their destination IP addresses. An access point is a device that connects wireless devices to a wired network and acts as a bridge between the two. References: 1: Aruba Certified Network Technician (ACNT) Study Guide, page 282: Aruba Certified Network Technician (ACNT) Study Guide, page 303: Aruba Certified Network Technician (ACNT) Study Guide, page 32. : Aruba Certified Network Technician (ACNT) Study Guide, page 29. : Aruba Certified Network Technician (ACNT) Study Guide, page 29. : Aruba Certified Network Technician (ACNT) Study Guide, page 94.

To access the second interface of a one-rack-unit standalone ArubaOS-CX switch, you should enter the command interface 0/0/2. This command specifies the interface name in the format of interface //, where  is the chassis number,  is the module number, and  is the port number. For a one-rack-unit standalone switch, the chassis number is always 0, and the module number is also 0 for the front panel ports. The port number starts from 1 and increments by 1 for each port. Therefore, the second interface of the switch is named interface 0/0/2. The other options are incorrect because they do not follow the correct interface naming convention for a one-rack-unit standalone switch. References: ArubaOS-CX 10.05 Command-Line Interface Guide 6200 Switch Series, ArubaOS-CX Switches - Configuring for initial access and performing a software upgrade

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 IP address 10.0.128.0/23 is a Class A private address with a subnet mask of 255.255.254.0. This means that the network prefix is 10.0.128.0 and the host identifier is the last 9 bits of the address. To find the number of IP assignable addresses, we need to subtract 2 from the total number of possible hosts, which is29=512. This is because the network address (10.0.128.0) and the broadcast address (10.0.129.255) are reserved and cannot be assigned to any host. Therefore, the number of IP assignable addresses is 512 - 2 = 510.References:IP Subnet Calculator,CIDR Calculator for IPv4 addresses,Free online IPv4 subnet calculator

Local-based management refers to managing a network device directly from the device itself, using tools such as console port, web interface, or command-line interface. Server-based management refers to managing a network device remotely from a centralized server, using tools such as Windows Admin Center, System Center, or Azure Arc123. The differences between these two types of management are:

• Local-based management can use the device’s console port, which is a physical connection that allows access to the device even when the network is down or the device is not configured. Server-based management cannot use the console port, as it relies on network connectivity and protocols4.
• Server-based management can monitor multiple devices at once, using a single dashboard or interface that shows the status, performance, and configuration of all the devices in the network. Local-based management can only monitor one device at a time, using the device’s own tools123.

References:

1: Cloud vs Server: Learn the Key Differences and Benefits - Parallels 2: Windows Server management overview | Microsoft Learn 4: 5 Benefits of Server-Based Local Access Networks for Small … - Versatech 3: What is Windows Admin Center | Microsoft Learn

The command to access the second interface of the third slot in a modular ArubaOS-CX switch is interface 1/3/2. This is because the interface numbering format for modular switches is interface slot/module/port, where slot is the chassis slot number, module is the module number within the slot, and port is the port number within the module1. The slot number starts from 1, the module number starts from 0, and the port number starts from 12. Therefore, the second interface of the third slot is interface 1/3/2. The other options are incorrect because they do not follow the correct interface numbering format. References: AOS-CX 10.06 Command-Line Interface Guide 8320, 8

IPv4 or Internet Protocol version 4 is the fourth version of the Internet Protocol that is used to identify and communicate with devices on the Internet. IPv4 uses a 32-bit address space, which means that each IPv4 address consists of 32 binary digits or bits. These bits can be expressed in different notations, such as decimal, hexadecimal, or binary. The most common notation is the dot-decimal notation, which divides the 32 bits into four groups of eight bits, called octets, and separates them by periods. For example, the IPv4 address 172.16.254.1 is equivalent to the binary address 10101100.00010000.11111110.00000001. The 32-bit address space of IPv4 allows for 2^32or 4,294,967,296 possible addresses, but some of them are reserved for special purposes, such as private networks or multicast addresses12345 References: https://en.wikipedia.org/wiki/Internet_Protocol_version_4

https://www.geeksforgeeks.org/what-is-ipv4/

 Wi-Fi is a wireless networking protocol that uses radio waves to communicate data over the air. Radio waves are electromagnetic waves that have different characteristics depending on their amplitude, phase, and frequency. Amplitude is the height of the wave, phase is the position of the wave relative to a reference point, and frequency is the number of cycles of the wave per second. To transmit data using Wi-Fi, these characteristics are modulated, or changed, according to a predefined scheme that encodes bits of information. For example, a high amplitude wave can represent a 1 bit, and a low amplitude wave can represent a 0 bit. Similarly, a positive phase shift can represent a 1 bit, and a negative phase shift can represent a 0 bit. Likewise, a high frequency wave can represent a 1 bit, and a low frequency wave can represent a 0 bit. By modulating these characteristics, Wi-Fi can transmit data in binary form over the air. Different modulation schemes can achieve different data rates and reliability, depending on the channel conditions and interference. Some common modulation schemes used by Wi-Fi are Binary Phase Shift Keying (BPSK), Quadrature Phase Shift Keying (QPSK), Quadrature Amplitude Modulation (QAM), and Orthogonal Frequency Division Multiplexing (OFDM). References: Understanding Wi-Fi and How It Works, Introduction to Wi-Fi Wireless Networking, Wireless Communication - Overview, Wireless Communication | Set 1.

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