Cisco CCNA (200-301)Network AccessHard
A network administrator is troubleshooting a wireless client connectivity issue. The client is unable to obtain an IP address from the DHCP server. The WLC GUI shows the client associated with an AP, but its status is 'Client IP Learn Failed'. Which of the following is the MOST likely cause of this issue?
- AThe VLAN for the client's SSID is not correctly configured or allowed on the trunk to the WLC or AP.
- BThe client is using a static IP address outside the DHCP scope.
- CThe WLAN is configured with an incorrect WPA2 Pre-Shared Key.
- DThe AP has lost its CAPWAP connection to the WLC.
Show answer & explanationAnswer & explanation
Correct answer: A. The VLAN for the client's SSID is not correctly configured or allowed on the trunk to the WLC or AP.
If the client is associated but 'IP Learn Failed', it indicates a Layer 2 connection is established, but Layer 3 (IP address acquisition) is failing. This often points to VLAN misconfiguration, where the client's VLAN traffic cannot reach the DHCP server, usually due to trunking issues between the AP/WLC and the rest of the network.
Why the other options are wrong
- B. If the client had a static IP, it would not be trying to learn one via DHCP, and the WLC would likely not report 'IP Learn Failed' in this context.
- C. An incorrect PSK would prevent association entirely; the client would not even reach the 'IP Learn Failed' stage.
- D. If the AP lost its CAPWAP connection, clients would not be able to associate with it at all.
Wireless Client IP Learn Failure
When a wireless client associates with an AP but fails to obtain an IP address, it typically indicates a Layer 2 issue preventing DHCP communication, commonly a VLAN or trunking misconfiguration.
- Client associates, but no IP.
- Points to Layer 2/3 boundary issue.
- Commonly VLAN/trunking problem.
Memory trick: VLANs Often Cause Layer 3 Negation during IP acquisition.