Which command is used to disable Cisco Discovery Protocol (CDP) on a Cisco router?
A. disable cdp
B. no cdp run
C. no cdp enable
D. no cdp advertise-v2
Correct Answer: B
The no cdp run command is used to disable CDP on a Cisco router globally. CDP is a Layer 2 (Data Link layer) protocol that discovers information about neighboring network devices.
CDP does not use network layer protocols to transmit information because it operates at the Data Link layer. Therefore, it is useful to determine information about directly connected
Cisco network devices, because it can operate when network protocols have not been configured or are misconfigured. The show cdp neighbors detail command is used to view the
IP addresses of the directly connected Cisco devices.
The no cdp advertise-v2 command disables CDPv2 advertisements. It will not disable the protocol globally.
The no cdp enable command is used to disable CDP on an interface. In a situation where CDP needs to be disabled on a single interface only, such as the interface leading to the
Internet, this command would be executed from interface configuration mode for that specific interface. It will not disable the protocol globally. For example, to disable CDP for only the
serial0 interface, the command sequence would be:
Router(config)#interface serial 0
Router(config-if)no cdp enable
The disable cdp command is not a valid Cisco command.
LAN Switching Fundamentals
Configure and verify Layer 2 protocols
Cisco > Cisco IOS Network Management Command Reference > show cdp neighbors