220-1101 Hardware and Network Troubleshooting Practice Question
A user reports that their desktop workstation loses network connectivity intermittently, often occurring when the user bumps the desk or moves the Ethernet cable. The link light on the NIC sometimes flickers and occasionally turns off for a few seconds during these events. The technician has already replaced the Ethernet cable with a known-good one and tested a different port on the same switch; the problem persists. Which of the following is the MOST likely cause of the issue?
⚠ Common exam trap
Many candidates assume a physical layer issue must be the cable or switch port, but the question explicitly states those were already replaced, forcing the correct answer to be the NIC port itself.
Answer choices
Why each option matters
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
The NIC port on the workstation has damaged or loose pins causing intermittent connection
The symptom of losing connectivity when the desk is bumped or the cable is moved, combined with the link light flickering or turning off, points to a physical layer issue at the NIC port. Since the cable and switch port have already been replaced and the problem persists, the most likely cause is a damaged or loose pin inside the RJ45 jack on the workstation's NIC. This creates an intermittent electrical contact that breaks under vibration or movement.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✓
The NIC port on the workstation has damaged or loose pins causing intermittent connection
Why this is correct
Inside the workstation's RJ-45 Ethernet jack, the eight gold-plated pins can become bent, broken, or lose their spring tension over time. Any slight vibration or physical bump of the desk or rear of the case can shift the connector just enough to break contact with the modular plug's terminals, dropping the link and turning off the link LED. Since the issue persisted after trying a known-good replacement cable and an alternate switch port, the fault is isolated to the onboard NIC connector itself, a classic Layer 1 intermittent fault.
- ✗
The switch port is failing intermittently
Why it's wrong here
An intermittent switch port could certainly cause the link LED to drop and connectivity to vanish, but the technician tested a different port on the same switch and the user's symptom continued. If the original switch port were at fault, moving the cable to a healthy port would have restored stable operation, assuming no other factors changed. Additionally, the loss of link is provoked by physical movement at the workstation, which would not affect a failing port's internal electronics. Therefore, this possibility is ruled out as the root cause.
- ✗
The workstation has a duplicate IP address on the network
Why it's wrong here
A duplicate IP address creates a logical conflict at Layer 3, causing the OS to send address-resolution warnings and intermittent loss of traffic when both hosts respond, but it has no effect on the physical link state. The link LED is driven by the NIC's PHY and remains lit whenever the Ethernet link is established, even during IP conflicts. Furthermore, a duplicate-IP condition would not be triggered by jostling the desktop, and it would not clear by replacing the cable or switching ports. Because the user's symptom includes the link light going off, this explanation is incorrect.
- ✗
The DNS server settings are incorrect
Why it's wrong here
DNS settings reside purely in the software stack and control how hostnames are resolved to IP addresses; incorrect DNS would cause name-resolution failures, not a total loss of link or a dark link LED. The NIC still maintains a solid Ethernet carrier and passes traffic to any known IP address, so physical movement of the case would not affect DNS behavior. Replacing cables or trying different switch ports would have no diagnostic bearing on a DNS misconfiguration. This symptom set points to the physical layer rather than an application-layer name-resolution problem.
Quick reference
OSI Model Reference
| Layer | Name | PDU | Key Protocols / Devices |
|---|---|---|---|
| 7 | Application | Data | HTTP, HTTPS, DNS, SMTP, FTP, SSH |
| 6 | Presentation | Data | TLS / SSL, JPEG, ASCII encoding |
| 5 | Session | Data | NetBIOS, RPC, SIP |
| 4 | Transport | Segment / Datagram | TCP, UDP |
| 3 | Network | Packet | IP, ICMP, OSPF — Routers |
| 2 | Data Link | Frame | Ethernet, Wi-Fi, PPP — Switches, Bridges |
| 1 | Physical | Bits | Cables, NICs, Hubs, Repeaters |
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Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
This 220-1101 practice question is part of Courseiva's free CompTIA certification practice question bank. Courseiva provides original exam-style practice questions with explanations, topic-based practice, mock exams, readiness tracking, and study analytics to help learners prepare for the 220-1101 exam.