Cisco CCNA (200-301)Network AccessHard
A network engineer is troubleshooting a connectivity issue between a workstation and a server. Both are connected to a Cisco Catalyst switch. The engineer suspects a VLAN mismatch. Which CDP-related log message would confirm a native VLAN mismatch on a trunk port?
- A%CDP-4-NATIVE_VLAN_MISMATCH
- B%CDP-4-DUPLEX_MISMATCH
- C%CDP-4-POWER_MISMATCH
- D%CDP-4-VERSION_MISMATCH
Show answer & explanationAnswer & explanation
Correct answer: A. %CDP-4-NATIVE_VLAN_MISMATCH
The `%CDP-4-NATIVE_VLAN_MISMATCH` syslog message is specifically generated by CDP when it detects that the native VLAN configured on a trunk port does not match the native VLAN advertised by the directly connected neighbor's trunk port.
Why the other options are wrong
- B. Indicates a duplex setting mismatch, not a VLAN issue.
- C. Relates to Power over Ethernet (PoE) capabilities, not VLANs.
- D. Indicates a mismatch in CDP protocol versions, not native VLANs.
CDP Error Messages
Cisco Discovery Protocol (CDP) can generate syslog messages to alert administrators of certain inconsistencies or mismatches with directly connected Cisco devices.
- CDP operates at Layer 2 and discovers directly connected Cisco devices.
- It reports information like device ID, platform, capabilities, and interface information.
- Specific messages like `NATIVE_VLAN_MISMATCH` help in troubleshooting trunking issues.
Memory trick: CDP: See Discrepancies, Pinpoint Problems.