Which command displays the status of all interfaces on a router?

The command that displays the status of all interfaces on a router is "show interfaces." When you enter this command in the command-line interface of a Cisco router, it provides detailed information about each interface, including its operational status, protocol status, bandwidth, and any errors that may have occurred. This command is essential for diagnosing interface issues, as it gives a comprehensive overview of both the state and the configuration of all the interfaces on the device.

In contrast, "show ip interface brief" offers a summarized view of the interface status and IP addresses, but it lacks the detailed information that "show interfaces" provides. "Show running-config" reveals the current configuration of the router but does not focus specifically on the interface status. Lastly, the "show version" command delivers information about the system's software and hardware version rather than interface details. Therefore, "show interfaces" is the most appropriate command for assessing the status of all interfaces on a router.