Which of the following protocols operates on port 445?

The Server Message Block (SMB) protocol operates on port 445. SMB is a network file sharing protocol that allows applications to read and write to files and also to request services from server programs in a computer network. It is widely used for sharing files, printers, and authenticating users in Windows environments.

Port 445 is specifically designated for SMB over TCP, making it essential for modern Windows networking operations, including access to shared resources and files on remote computers. Understanding the port assignments for various protocols is important because it helps in configuring firewalls and troubleshooting network issues effectively.

The other protocols listed, such as FTP, SNMP, and LDAP, operate on different ports: FTP typically uses ports 21 (and occasionally 20), SNMP generally uses port 161, and LDAP typically uses port 389. This distinction emphasizes the importance of recognizing which services correspond to which ports in network management and security contexts.