Cisco CCNA Layer 2 Discovery Protocols (CDP and LLDP)

Question 1

Which command shows the IP address, IOS version, and platform of directly connected Cisco neighbors?

Accepted Answer

show cdp neighbors detail

Answer

'show cdp neighbors detail' (or 'show cdp entry *') shows each neighbor's management IP address, software version, platform, and capabilities. The plain 'show cdp neighbors' summary leaves out the IP address and IOS version.

Question 2

LLDP is defined by which standard?

Accepted Answer

IEEE 802.1AB

Answer

LLDP (Link Layer Discovery Protocol) is the vendor-neutral standard IEEE 802.1AB. 802.1Q is VLAN trunking, 802.3af is PoE, and 802.1X is port-based authentication.

Question 3

What are the default CDP advertisement timer and holdtime on Cisco IOS?

Accepted Answer

60 seconds / 180 seconds

Answer

By default, CDP sends advertisements every 60 seconds and keeps neighbor information for 180 seconds (three times the timer). LLDP defaults are 30 seconds and 120 seconds.

Question 4

Which global configuration command enables LLDP on a Cisco switch, where it is often disabled by default?

Accepted Answer

lldp run

Answer

'lldp run' enables LLDP globally on Cisco IOS, the same way 'cdp run' enables CDP. Per-interface control uses 'lldp transmit' and 'lldp receive'.

Question 5

An engineer wants a switch interface to keep receiving LLDP frames but stop sending them. Which interface command does this?

Accepted Answer

no lldp transmit

Answer

LLDP controls transmit and receive separately on each interface. 'no lldp transmit' stops outgoing advertisements and still processes incoming ones. 'no lldp run' disables LLDP for the whole device.

Cisco CCNA Practice Test

Cisco CCNA Practice Test

Cisco CCNA Layer 2 Discovery Protocols (CDP and LLDP)