HPE3-U01 Exam Dumps : Aruba Certified Network Technician Exam (ACNT)

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

 The dual-band IEEE WLAN standard that provides up to 4.8 Gbps of theoretical data rate is 802.11 be, also known as Wi-Fi 7. This standard is an amendment to the IEEE 802.11-2020 standard that aims to improve the performance, efficiency, and reliability of WLANs operating in the 2.4 GHz and 5 GHz frequency bands. Some of the key features of 802.11 be include:

• Enhanced multi-user multiple-input multiple-output (MU-MIMO) that supports up to 16 spatial streams and 37 users per channel
• Orthogonal frequency division multiple access (OFDMA) that allows multiple users to share the same channel with different subcarrier allocations
• 320 MHz channel bandwidth that enables higher data rates and spectral efficiency
• 4096 quadrature amplitude modulation (QAM) that increases the number of bits per symbol
• Multi-link operation that allows a device to connect to multiple access points (APs) simultaneously
• Enhanced power saving mechanisms that reduce the energy consumption and extend the battery life of devices

The other options are incorrect because they do not provide the same level of data rate as 802.11 be. 802.11 ac, or Wi-Fi 5, supports up to 1.73 Gbps of data rate in the 5 GHz band with 160 MHz channel bandwidth and 256 QAM. 802.11 ax, or Wi-Fi 6, supports up to 9.6 Gbps of data rate in both 2.4 GHz and 5 GHz bands with 160 MHz channel bandwidth, 1024 QAM, and OFDMA, but it is not a dual-band standard as it also supports the 6 GHz band. 802.11 n, or Wi-Fi 4, supports up to 600 Mbps of data rate in both 2.4 GHz and 5 GHz bands with 40 MHz channel bandwidth and 64 QAM. 802.1 lax and 802.1 In are not valid IEEE WLAN standards. References: IEEE 802.11be Extremely High Throughput: The Next Generation of Wi-Fi Technology Beyond 802.11ax, Wi-Fi Timeline, IEEE 802.11-2020

Layer 2 encapsulation is the process of adding a header and a trailer to the data coming from the upper layer (Layer 3) before sending it over the physical medium. The header and the trailer contain information such as source and destination MAC addresses, error detection, and protocol type. The devices that perform Layer 2 encapsulation are usually switches, bridges, or network interface cards (NICs). In the given network diagram, the PC is sending a message to the server. The PC first adds a Layer 2 header and trailer to the data and sends it to Switch-1. Switch-1 performs Layer 2 encapsulation again before forwarding it to the router. The router operates at Layer 3 and does not perform Layer 2 encapsulation. It only removes the Layer 2 header and trailer, checks the destination IP address, and forwards the packet to the next hop. The packet then reaches Switch-2, where Layer 2 encapsulation occurs again before it is sent to the server. The server also performs Layer 2 de-encapsulation by removing the header and trailer and passing the data to the upper layer. Therefore, the devices that have performed Layer 2 encapsulation by the time the message arrives at the server are Switch-1 and Switch-2. References: Understanding Data Link Layer Encapsulation, How Data Encapsulation & De-encapsulation Works?, HDLC Protocol and Encapsulation method Explained