Refer to the exhibit. If CDP is enabled on all devices and interfaces, which devices will appear in the output of a show cdp neighbors command issued from R2?
正解:C
Explanation/Reference: Explanation: A Cisco device enabled with CDP sends out periodic interface updates to a multicast address in order to make itself known to neighbors. Since it is a layer two protocol, these packets are not routed. So the devices detected would be immediate connected neighbors.