Which Cisco IOS command makes all interfaces passive by default?

The command that makes all interfaces passive by default in Cisco IOS is "passive-interface default." This command is used in conjunction with routing protocols, such as EIGRP or OSPF, to control the way interfaces participate in routing updates. When you configure an interface as passive, the router will not send routing updates out of that interface, although it can still receive updates. This is particularly useful in scenarios where you want to prevent unnecessary routing traffic over certain links, such as on point-to-point or stub networks.

By implementing this command, the network administrator can ensure a cleaner routing table and enhance network efficiency, as only interfaces that are explicitly set to send updates will do so. This allows the network to be more secure and reduces unnecessary overhead. As a result, using "passive-interface default" provides a straightforward method for managing the behavior of all interfaces without needing to configure each one individually.

Other options do not accurately depict the command syntax or functionality required to set all interfaces to passive by default, reinforcing the understanding of command structures in Cisco IOS.