How to Locate an Unlabeled Switchport When NIC Link Lights Are Off?
A user cannot connect to the network, although others in the office are unaffected. The network technician sees that the link lights on the NIC are not on. The technician needs to check which switchport the user is connected to, but the cabling is not labeled. Which of the following is the best way for the technician to find where the computer is connected?
Community Votes
75% of anonymous learners picked answer D. Votes are pick records left by other test-takers — they are not the verified answer.
Community Insight
The question tests whether you understand that link lights off means the physical layer is down, so logical mapping methods like CAM/ARP tables may be unreliable; the correct answer is to trace the cable with a tone generator.
When a user's NIC link lights are off and cabling is unlabeled, the best way to locate the switchport is to use a tone generator to physically trace the cable. Community consensus favors tone generation over CAM table lookup because the switch may not have learned the MAC address without an active link.
The most common wrong answer is C, looking up the MAC address in the CAM table. Test takers forget that a down link means the switch likely hasn't learned the MAC address, and a stale CAM entry may point to the wrong port or be absent.
Community Discussion (5 comments)
Comments & Corrections
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Expert Analysis
Why the Answer Is Correct
Option D (tone generator) is the best answer because the NIC link lights are off, indicating a physical-layer problem such as a disconnected or damaged cable. A tone generator and probe allow the technician to physically trace the cable from the computer to the exact switchport, even when there is no active link. Comment [1] correctly notes that if link lights aren't on, the device may not be in the CAM table, making tone generation the right choice. Comment [2] adds that the tone generator provides a guaranteed solution, whereas a CAM lookup is not guaranteed.Why the Other Options Are Wrong
Option A (ARP table) maps IP addresses to MAC addresses, not to switchports, and requires IP connectivity that is likely absent when the link is down. Option B (cable tester) verifies cable continuity but does not identify the specific switchport among many unlabeled cables in a patch panel. Option C (CAM table) could work if the switch had learned the MAC address, but with link lights off the port is likely down, so the CAM entry may be missing or stale. Therefore, physical tracing with a tone generator is the most reliable approach.Community Comment Notes
Comment [1] and [2] support D, highlighting that the CAM table may not contain the MAC address when the link is down. Comment [3] raises a valid concern that a broken cable might prevent a tone from passing through, but a tone generator can still identify the cable at the switch side. Comment [4] explains the CAM table concept but overlooks the fact that the link is currently down, which undermines the reliability of that method. The most useful comments agree that tone generation is the best first step in this physical-layer troubleshooting scenario.Official Reference
Exam Strategy
Look for physical-layer clues first. If link lights are off, avoid answers that rely on logical tables; choose the physical trace tool. Remember that a tone generator and probe is the standard way to identify an unlabeled cable at a switchport.