What command is used to configure an IP address on an interface?

The command used to configure an IP address on an interface is indeed "ip address ip-address subnet-mask." This command is an essential part of Cisco IOS and is used in interface configuration mode to assign an IP address and its corresponding subnet mask to the specific interface.

When configuring a router or switch, it is common to enter global configuration mode first, then access the desired interface using the "interface" command. After selecting the interface (for example, "interface GigabitEthernet0/1"), the "ip address" command is executed followed by the specific IP address and its subnet mask. This results in the interface being assigned a unique IP address that allows it to participate in the network communication within the specified subnet.

The other commands provided do not adhere to the standard Cisco syntax and therefore would not successfully configure an IP address. Using "set ip-address subnet-mask" or "define ip-address subnet-mask" would not be recognized by the Cisco IOS, as these terms are not used for IP address configuration. Similarly, "configure ip-address subnet-mask" does not match the correct command structure for setting an IP address on an interface.