Question

Difficulty: EasyWired and Wireless Network Issues

A network technician is troubleshooting a desktop computer that has lost network connectivity. Upon inspecting the back of the computer, the technician observes that the link light on the Ethernet network interface card (NIC) is completely off. Which of the following should the technician perform FIRST?

  1. Check if the Ethernet cable is securely connected at both the computer and the wall jackAnswer
  2. B
    Run ipconfig /release and ipconfig /renew to obtain a new IP address from the DHCP server
  3. C
    Change the wireless network channel on the router to reduce frequency interference
  4. D
    Reconfigure the local router to act as a Layer 2 switch to bypass network boundary restrictions

Answer

Check if the Ethernet cable is securely connected at both the computer and the wall jack
An unlit link light indicates a failure at Layer 1 (Physical Layer) of the OSI model. Verifying that the cable is properly seated and undamaged is the logical first step to establish physical layer connectivity.

Step-by-Step Solution

1
Identify the primary symptom
The Ethernet NIC link light is unlit, indicating no physical connection signal.
Unlit link lights point directly to a Layer 1 physical layer failure.
2
Select the appropriate troubleshooting step
Inspect and reseat physical cabling.
CompTIA troubleshooting methodology specifies starting with the physical layer before moving to higher-level logical configurations.

Key Concept

Wired Network Physical Layer Diagnostics
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