What is one purpose of the TCP three-way handshake?
The three-way handshake in Transmission Control Protocol (also called the three message handshake) is the method used to establish and tear down network connections. This handshaking technique is referred to as the 3-way handshake or as “SYN-SYN-ACK” (or more accurately SYN, SYN-ACK, ACK). The TCP handshaking mechanism is designed so that two computers attempting to communicate can negotiate the parameters of the network connection before beginning communication. This process is also designed so that both ends can initiate and negotiate separate connections at the same time.