CompTIA Network+ (N10-009)Network TroubleshootingEasy
A user reports that their workstation is unable to connect to the network. The technician inspects the workstation and confirms that the network cable is securely plugged into both the workstation and the wall jack. The link lights on both the workstation's NIC and the switch port are unlit. Which of the following is the MOST likely cause?
- AThe DHCP server is down.
- BIncorrect IP address assigned to the workstation.
- CA faulty network cable.
- DThe workstation's operating system is corrupted.
Show answer & explanationAnswer & explanation
Correct answer: C. A faulty network cable.
Unlit link lights on both the NIC and the switch port, despite the cable being plugged in, indicate a complete lack of physical layer connectivity. The most common and simplest cause for this symptom is a faulty network cable.
Why the other options are wrong
- A. A downed DHCP server would prevent IP address assignment but would not affect the physical link light status.
- B. Incorrect IP address would not prevent link lights from illuminating, as it's a Layer 3 issue.
- D. An OS corruption might prevent network services from running, but the NIC's link light, being a hardware indicator, would still illuminate if there was a physical link.
Unlit Link Lights
Indicates a lack of physical layer (Layer 1) connectivity between two network devices.
- Common causes include faulty cables, incorrect cable type, or disabled ports.
- Troubleshoot by checking cables, ports, and interface status.
- Prevents any higher-layer network communication.
Memory trick: No light, no life for the network cable.