What does a three-way handshake accomplish in networking?

A three-way handshake accomplishes the process of establishing a reliable connection between two devices in a network. Specifically, this involves the exchange of three packets:

1. The initiating device sends a SYN (synchronize) packet to the target device, indicating that it wants to establish a connection.
2. The target device responds with a SYN-ACK (synchronize-acknowledge) packet, confirming that it acknowledges the request and is also ready to establish a connection.

3. Finally, the initiating device sends an ACK (acknowledge) packet back to the target device, finalizing the process and confirming that the connection is established.

This mechanism is pivotal for protocols such as TCP (Transmission Control Protocol), which require a reliable connection to ensure that data is transmitted accurately and in the correct order. The three-way handshake is essential for setting up this kind of connection before any actual data transfer begins, ensuring both parties are ready for communication and can keep track of the connection state.

The other options do not accurately describe the purpose of the three-way handshake. The method of securing data transmissions is more closely related to encryption processes and protocols, not the handshake itself. A denial of service attack involves attempts to disrupt service and is not relevant to establishing connections.