Name a common method used for network security authentication.

WPA2 (Wi-Fi Protected Access II) is a widely used security protocol for wireless networks that provides a robust method for authentication as well as encryption. It enhances the security of a network by implementing the Advanced Encryption Standard (AES) for encryption, which helps protect user data and communication from unauthorized access.

WPA2 requires the use of a pre-shared key (PSK) or a RADIUS server for enterprise environments, ensuring that only authenticated and authorized users can access the network. This capability to authenticate users and encrypt data transmission makes it a crucial method for maintaining network security in wireless environments.

The other options do not primarily focus on user authentication. SSL is designed for securing communication over a computer network, HTTP is a protocol for transferring data on the web without authentication features, and FTP serves to transfer files but lacks built-in security measures for user authentication. Thus, WPA2 stands out as a preferred method for ensuring that only legitimate users can connect to and communicate over a wireless network.