Which protocol is commonly used to transfer files over a network securely?

The correct choice is SSH, which stands for Secure Shell. This protocol is designed to allow secure access and transfer of files over a network, providing encrypted communication between a client and a server. SSH is frequently used for secure logins, remote command execution, and secure file transfers.

While FTP (File Transfer Protocol) is a traditional protocol for transferring files, it does not encrypt the data being sent, making it vulnerable to eavesdropping. TFTP (Trivial File Transfer Protocol) is even simpler than FTP and does not have any authentication or encryption mechanisms, which compromises security significantly. NTP (Network Time Protocol) serves a different purpose altogether, focusing on synchronizing clocks over a network rather than transferring files.

Using SSH for file transfers, specifically through its secure file transfer capability (SFTP), ensures that sensitive information is protected during transmission, making it the go-to protocol for secure file transfers over a network.