Question

Difficulty: MediumWired and Wireless Network Issues

A technician is troubleshooting a desktop computer in an enterprise office that lost network connectivity following a switch maintenance window. Running `ipconfig` displays an IP address of 169.254.4.15169.254.4.15 and a subnet mask of 255.255.0.0255.255.0.0. Additionally, the technician observes that the link light on the workstation's network interface card (NIC) is unlit. Which of the following actions should the technician perform to address these issues? (Select TWO.)

  1. Inspect the physical network cable connection and switch port link LEDs to verify physical layer connectivity.Answer
  2. B
    Reconfigure the local client's preferred DNS server setting to point to the 169.254.0.0/16 default gateway.
  3. Verify the VLAN tags and DHCP relay helper address configuration on the newly maintained switch.Answer
  4. D
    Adjust the 2.4 GHz wireless access point to transmit on channel 4 to avoid interference with the Ethernet switch.

Answer

The technician should inspect the physical network cable and switch port link LEDs to verify physical layer connectivity, and verify the VLAN tags and DHCP relay helper configuration on the new switch to restore DHCP address assignment.
Inspecting physical cables and switch port LEDs addresses the unlit link light by verifying physical layer connectivity. Checking switch VLAN tagging and DHCP relay configuration addresses the APIPA address assignment (169.254.x.x169.254.x.x) by restoring communication between the client and the DHCP server across subnets.

Step-by-Step Solution

1
Diagnose physical layer status based on NIC link light symptom
The unlit link LED indicates an inactive physical connection between the workstation NIC and the switch port.
Physical connectivity must be established first before higher-layer protocols can function.
2
Diagnose IP addressing failure based on APIPA address presence
The 169.254.4.15169.254.4.15 IP address confirms the client failed to receive an IP lease from a DHCP server.
Switch maintenance may have reset or misplaced VLAN trunking or DHCP relay settings.

Key Concept

Wired Network Troubleshooting and APIPA Recovery
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