To configure a speed of 100 Mbps on an interface, what command is used?

To configure an interface to operate at a speed of 100 Mbps, the command used is simply "speed 100." This command is part of the interface configuration mode in Cisco IOS (Internetwork Operating System) and specifies the desired speed for the interface.

When configuring network interfaces, it is crucial to correctly specify parameters such as speed and duplex settings to ensure optimal performance and compatibility with connected devices. The command "speed 100" specifically sets the interface to a speed of 100 Mbps, which is a common setting for Fast Ethernet connections.

In contrast, other options presented do not conform to the syntax used in Cisco IOS. For example, "set speed 100" and "configure speed 100" do not represent valid commands in this context, as Cisco IOS does not use "set" or "configure" as a prefix for configuring interface parameters. The "duplex" option is unrelated to speed; it pertains to the data transmission method (half-duplex or full-duplex) and does not refer to the speed configuration itself. Thus, understanding the correct command syntax is crucial for proper device configuration and management.