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220-1201 Practice Question: That their computer connected to a wall jack…
A user reports that their computer connected to a wall jack works fine, but when they move the computer to a different desk and plug into a different wall jack, there is no network connectivity. The switch port shows no link light. What is the most likely cause?
⚠ Common exam trap
The exam often tests the misconception that a faulty NIC or crossover cable is the cause, but the key clue is that the computer works at one jack and fails at another, isolating the problem to the new cabling path rather than the endpoint or switch configuration.
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 wall jack is terminated incorrectly.
The most likely cause is that the wall jack at the new desk is terminated incorrectly, such as a miswired T568A/T568B standard or a broken punch-down connection. Since the computer works at the original jack and the switch port shows no link light, the issue is isolated to the new cabling path, not the NIC or switch configuration. Incorrect termination can cause a physical layer failure, preventing the switch from detecting a carrier signal.
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 computer's NIC is faulty.
Why it's wrong here
If the computer's Network Interface Card (NIC) were faulty, it would likely exhibit connectivity problems at any location, not just the new desk. Since the user reports the computer worked correctly at its previous location, the NIC itself is probably functional, indicating the issue lies elsewhere in the network path specific to the new connection point. A faulty NIC would typically manifest as no link light or no data transfer even with a known good cable and port.
- ✗
The patch cable is not a crossover cable.
Why it's wrong here
Modern network devices, including most Network Interface Cards (NICs) and switches, incorporate a feature called Auto-MDIX (Automatic Medium-Dependent Interface Crossover). This technology automatically detects the cable type and configures the port's transmit and receive pairs accordingly, eliminating the need for a specific crossover cable when connecting similar devices or a computer directly to a switch. Therefore, the absence of a crossover cable would not prevent a link.
- ✓
The wall jack is terminated incorrectly.
Why this is correct
An incorrectly terminated wall jack means that the individual wires within the Ethernet cable are not connected to the correct pins on the RJ-45 connector according to T568A or T568B standards. This miswiring prevents proper electrical continuity for data transmission and reception, resulting in no physical link being established between the computer's NIC and the network switch. Consequently, the link light on both the NIC and the switch port would remain unlit.
- ✗
The switch port is administratively down.
Why it's wrong here
An administratively down switch port means that a network administrator has intentionally disabled the port through software configuration, preventing any traffic from passing. While this is a possibility, it is generally less probable than a physical layer issue like incorrect termination, especially if other ports on the same switch are operational. A port being administratively down would also typically prevent a link light from illuminating, but the context of moving to a new desk points more strongly to a physical installation 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 |
Go deeper
Related to this question
Learn chapter
Mobile Device Connectivity
Key term
CAN
A CAN (Controller Area Network) is a robust vehicle bus standard designed to allow microcontrollers and devices to communicate with each other without a host computer.
Key term
Switch
A switch is a networking device that connects devices on a local area network and uses MAC addresses to forward data only to the intended recipient.
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JA
Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
This 220-1201 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 220-1201 exam.