Final answer:
The command to disable directed broadcasting on a Cisco router is 'no ip directed-broadcast'. This command prevents potential misuse of directed broadcasting, which can be used for DoS attacks.
Step-by-step explanation:
The command to disable directed broadcasting on a Cisco router is no ip directed-broadcast.
Directed broadcasting is a feature that allows a host to send a broadcast message to all the hosts on a remote network. However, it can be misused as a means of conducting DoS (Denial of Service) attacks. By using the no ip directed-broadcast command, you are disabling this feature and preventing any potential misuse.
For example, if you input the command no ip directed-broadcast on a Cisco router, it will disable the directed broadcasting functionality.