What command would you use to configure an interface with an IP address on a Cisco router?

The command to configure an interface with an IP address on a Cisco router is "ip address [IP address] [subnet mask]". This command is typically used in interface configuration mode, where the user specifies the IP address and its corresponding subnet mask.

This command directly assigns an IP address to the selected interface, thereby allowing the device to communicate on the network. By entering this command under the specific interface configuration context, you ensure that the settings are applied only to that particular interface, which is the correct way to manage IP configurations on Cisco devices.

The importance of using the correct syntax cannot be overstated. In Cisco IOS (Internetwork Operating System), commands follow specific formats and are case-sensitive, which means using an incorrect command would result in an error or a failure to apply the intended configuration.