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

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.

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

 The TCP three-way handshake is a process that is used in a TCP/IP network to create a connection between a client and a server. It involves the exchange of three packets: SYN, SYN-ACK, and ACK. The goal of the TCP three-way handshake is to establish a reliable, flow-controlled connection between the two endpoints. This means that the connection is able to ensure that the data is transmitted without errors, losses, or duplications, and that the data is sent at a rate that both sides can handle.

The TCP three-way handshake works as follows:

• The client initiates the connection by sending a SYN packet to the server. The SYN packet contains a random sequence number that indicates the starting point of the data that the client will send.
• The server responds to the client by sending a SYN-ACK packet. The SYN-ACK packet contains the server’s own sequence number and an acknowledgment number that is equal to the client’s sequence number plus one. This indicates that the server has received the client’s SYN packet and is ready to receive data from the client.
• The client completes the handshake by sending an ACK packet to the server. The ACK packet contains an acknowledgment number that is equal to the server’s sequence number plus one. This indicates that the client has received the server’s SYN-ACK packet and is ready to send data to the server.

After the TCP three-way handshake is completed, the connection is established and the data transfer can begin.

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

• TCP 3-Way Handshake Process - GeeksforGeeks
• TCP 3-Way Handshake (SYN, SYN-ACK,ACK) - Guru99
• Akamai Blog | What is a TCP Three-Way Handshake?
• What is a Three-Way Handshake? - Definition from Techopedia
• What is TCP 3-Way Handshake, Benefits, and Drawbacks? - Networking Signal