What Happens When CDP Interface on Adjacent Device is Configured without an IP Address

C

Although CDP is a Layer 2 protocol but we can check the neighbor IP address with the show cdp neighbor detail command. If the neighbor does not has an IP address then CDP still operates without any problem. But the IP address of that neighbor is not provided.

CDP ( Cisco Discovery Protocol) is a Cisco proprietary Layer 2 network protocol used to gather information about directly connected Cisco equipment. It is enabled by default on Cisco devices and allows them to share information about themselves with other directly connected Cisco devices.

When the CDP interface on an adjacent device is configured without an IP address, the CDP neighbor will still be discovered and identified by the local device, but it will not be able to provide IP address information for that neighbor. Therefore, option C is the correct answer.

CDP operates at the data link layer and does not require an IP address to function. CDP can discover and share information about neighboring Cisco devices, such as their platform, IP address, port ID, and capabilities, regardless of whether they have an IP address or not. However, without an IP address, the local device will not be able to obtain IP-related information about the neighbor device.

It is important to note that while CDP is a Cisco proprietary protocol, other vendors have similar protocols such as LLDP (Link Layer Discovery Protocol) that can also be used for network discovery and management.