Promiscuous mode is a network interface configuration in which the NIC passes all observed frames to the operating system, not only frames addressed to that host's MAC address. In investigations, this matters because promiscuous mode is commonly enabled by packet sniffers, certain intrusion tools, or misconfigured monitoring software, and it can indicate covert traffic capture on a host.

On UNIX/Linux systems, the traditional command used to view interface flags and status is ifconfig <interface name>. When an interface is set to promiscuous mode, ifconfig displays a PROMISC flag in the interface's status line, allowing an investigator to confirm whether the NIC is accepting all frames. This directly matches Kane's goal of checking if the interface is running in promiscuous mode.

The other commands do not provide this specific interface flag. nmap -sT localhost scans for open TCP ports, not interface modes. ipconfig is a Windows command (and does not take an interface name in that form to show PROMISC status), and it primarily reports IP configuration. netstat -i shows network interface statistics (packets, errors, drops) but typically does not explicitly indicate promiscuous mode. Therefore, the correct command is ifconfig <interface name> (C).