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Difficulty: HardWired and Wireless Network Issues

A network technician connects a newly imaged workstation to an Ethernet wall outlet in a multi-tenant corporate office. The network interface card (NIC) link light is solid green, indicating established physical connectivity. However, running `ipconfig` reveals that the workstation has an IPv4 address of 169.254.42.19169.254.42.19 with a subnet mask of 255.255.0.0255.255.0.0. All existing computers on the floor receive valid 10.15.20.x10.15.20.x addresses from a central server. Which of the following is the MOST likely cause of this issue?

  1. The switch port connected to the wall outlet is assigned to an isolated or incorrect VLAN that lacks an active DHCP server or relay agent.Answer
  2. B
    The workstation is sending hostname resolution requests to the DHCP server instead of querying the primary DNS server.
  3. C
    The physical network patch cable has suffered a complete open fault, preventing the NIC from establishing a hardware link.
  4. D
    The workstation requires an unmanaged Layer 2 switch rather than a router to connect its local subnet to the corporate network.

Answer

The switch port connected to the wall outlet is assigned to an isolated or incorrect VLAN that lacks an active DHCP server or relay agent.
An IP address of 169.254.42.19169.254.42.19 indicates APIPA, which occurs when a workstation fails to receive a response from a DHCP server. Since the NIC link light is solid green, the physical layer is functional. In a corporate environment, a workstation generating an APIPA address on a specific outlet while neighboring machines function normally indicates that the switch port is misconfigured to an isolated or incorrect VLAN that lacks an operational DHCP server or IP helper relay.

Step-by-Step Solution

1
Analyze the physical layer status from the scenario details.
The NIC link light is solid green, confirming that Physical Layer (Layer 1) connectivity between the workstation and the switch port is operational.
Establishing link light activity rules out disconnected cables, broken pins, or disabled switch ports.
2
Interpret the IP address assignment (169.254.42.19169.254.42.19).
Addresses in the range 169.254.0.1169.254.0.1 to 169.254.255.254169.254.255.254 represent APIPA (Automatic Private IP Addressing), assigned by the client OS when DHCP discovery times out.
APIPA indicates that the client broadcasted a DHCPDISCOVER packet but received no DHCPOFFER response from a server.
3
Evaluate why DHCP messages fail on a specific outlet while other hosts receive 10.15.20.x10.15.20.x addresses.
Because other devices on the floor receive valid IP leases, the central DHCP infrastructure is functional. The specific switch port is likely tagged for an unrouted VLAN or guest network missing a DHCP server/IP helper.
VLAN isolation prevents broadcast traffic (such as DHCPDISCOVER) from reaching servers in other VLANs unless a DHCP relay agent is configured.

Key Concept

APIPA Interpretation & VLAN Troubleshooting
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Topics

Wired and Wireless Network Issues

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