220-1101 Networking Practice Question
A user reports that their computer's internet speed is much slower than expected. A speed test shows 10 Mbps, but the ISP plan provides 100 Mbps. The technician tests a laptop directly connected to the ISP modem and gets 100 Mbps. The user's computer is connected to the network via a wall jack and patch panel. The technician checks the computer's NIC and sees it is negotiating at 10 Mbps. Which of the following is the MOST likely cause?
⚠ Common exam trap
The trap here is that candidates often blame the switch port configuration (Option C) or a virus (Option D) without recognizing that the NIC's negotiated link speed is a physical-layer indicator, not a throughput measurement, and the direct-connect test isolates the issue to the cable or wall jack path.
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 Ethernet cable is damaged or of poor quality.
The technician's laptop achieves 100 Mbps when directly connected to the ISP modem, proving the ISP service and modem are functioning correctly. The user's computer negotiates at only 10 Mbps, which is a classic symptom of a faulty or substandard Ethernet cable that fails to support 100BASE-TX signaling. Damaged or poor-quality cables often cause the auto-negotiation process to fall back to 10BASE-T, as the link pulses for 100 Mbps cannot be reliably exchanged.
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 Ethernet cable is damaged or of poor quality.
Why this is correct
A damaged or poor-quality Ethernet cable can introduce excessive attenuation, crosstalk, or signal reflections that corrupt frames at higher negotiated speeds. Auto-negotiation and error detection at the physical layer will often cascade the link down to 10 Mbps (or a half-duplex mode) to maintain stability, even if the cable still passes a continuity test. This makes it the most common cause of a dramatic speed mismatch, since it is both plausible and frequently observed in field troubleshooting.
- ✗
The NIC driver is out of date.
Why it's wrong here
An outdated NIC driver primarily affects software interfaces, protocol stack handling, or offload features and can cause slow throughput due to CPU-bound processing, but it does not change the physical layer auto-negotiation that determines link speed. The NIC's hardware and firmware manage the electrical signaling and negotiation independent of the driver; a defective driver typically results in connectivity loss or high interrupt rates, not a negotiated 10 Mbps link. Therefore, while a driver update might improve overall performance, it would not correct a link that has physically negotiated to 10 Mbps.
When this WOULD be correct
A user reports intermittent network connectivity or no link at all. The technician checks the NIC and sees it is not detected or shows errors. After updating the NIC driver, the issue is resolved. In that scenario, an outdated or corrupt driver is the most likely cause.
- ✗
The switch port is configured for 10 Mbps full-duplex.
Why it's wrong here
If the switch port were explicitly configured to 10 Mbps full-duplex, the NIC might indeed fall back to a 10 Mbps link because auto-negotiation would not discover a common higher speed. However, such a static configuration is an intentional administrative action that is extremely rare in a standard enterprise or home network, whereas a faulty cable is a natural and common failure mode. Unless there is direct evidence of a misconfigured port, it is not the most probable explanation; the symptom is also typically accompanied by duplex mismatch issues if the NIC remains in auto mode, making this a less likely root cause.
When this WOULD be correct
This option would be correct if the technician tested a laptop connected to the same switch port and also got 10 Mbps, or if the switch port was known to be manually configured for 10 Mbps full-duplex, and the user's NIC was capable of higher speeds.
- ✗
The computer has a virus consuming bandwidth.
Why it's wrong here
A virus consuming bandwidth operates at the application or transport layer, generating extra network traffic that saturates the link's throughput but does not alter the NIC's negotiated link speed, which remains at the hardware-negotiated physical rate. The NIC would still show a 100 Mbps or 1 Gbps link, but available capacity would be reduced by the malicious traffic. This would not force the adapter to re-negotiate downward to 10 Mbps; it would simply make the link appear slow due to congestion, so it cannot explain a fixed 10 Mbps link speed.
When this WOULD be correct
A virus consuming bandwidth would be correct if the user's computer showed normal link speed (e.g., 100 Mbps) but speed tests were slow, and other devices on the same network also experienced slowdowns, suggesting malware flooding the network.
Option-by-option analysis
Why each answer is right or wrong
Understanding why wrong answers are wrong — and when they would be correct — is what separates a 750 score from a 900. The 220-1101 exam frequently reuses these exact scenarios with slightly different constraints.
✓The Ethernet cable is damaged or of poor quality.Correct answer▾
Why this is correct
A damaged or poor-quality Ethernet cable can introduce excessive attenuation, crosstalk, or signal reflections that corrupt frames at higher negotiated speeds. Auto-negotiation and error detection at the physical layer will often cascade the link down to 10 Mbps (or a half-duplex mode) to maintain stability, even if the cable still passes a continuity test. This makes it the most common cause of a dramatic speed mismatch, since it is both plausible and frequently observed in field troubleshooting.
✗The NIC driver is out of date.Wrong answer — click to see why▾
Why this is wrong here
The technician already tested a laptop directly connected to the ISP modem and got 100 Mbps, ruling out ISP issues. The user's computer negotiates at 10 Mbps, indicating a physical layer problem (cable or connection) rather than a driver issue, which would typically cause no link or intermittent connectivity, not a fixed 10 Mbps negotiation.
★ When this WOULD be the correct answer
A user reports intermittent network connectivity or no link at all. The technician checks the NIC and sees it is not detected or shows errors. After updating the NIC driver, the issue is resolved. In that scenario, an outdated or corrupt driver is the most likely cause.
Why candidates choose this
Candidates may think outdated drivers can cause speed degradation, but drivers usually cause complete failure or instability, not a consistent lower speed negotiation. The specific 10 Mbps negotiation points to a cable or port issue.
✗The switch port is configured for 10 Mbps full-duplex.Wrong answer — click to see why▾
Why this is wrong here
The switch port being configured for 10 Mbps full-duplex would cause a consistent 10 Mbps link speed, but the technician tested a laptop directly connected to the ISP modem and got 100 Mbps, indicating the ISP and modem are fine. The issue is specific to the user's computer connection via the wall jack and patch panel, pointing to a cabling problem rather than a switch configuration issue.
★ When this WOULD be the correct answer
This option would be correct if the technician tested a laptop connected to the same switch port and also got 10 Mbps, or if the switch port was known to be manually configured for 10 Mbps full-duplex, and the user's NIC was capable of higher speeds.
Why candidates choose this
Candidates may confuse link speed negotiation with switch port configuration, thinking that a misconfigured switch port could force a lower speed, but in this scenario the issue is isolated to the user's connection path.
✗The computer has a virus consuming bandwidth.Wrong answer — click to see why▾
Why this is wrong here
The technician verified that a laptop directly connected to the ISP modem achieves 100 Mbps, ruling out ISP issues or bandwidth consumption. The user's computer negotiates at 10 Mbps via the wall jack, indicating a physical layer problem, not a virus.
★ When this WOULD be the correct answer
A virus consuming bandwidth would be correct if the user's computer showed normal link speed (e.g., 100 Mbps) but speed tests were slow, and other devices on the same network also experienced slowdowns, suggesting malware flooding the network.
Why candidates choose this
Candidates may assume slow internet is always caused by malware or background processes, overlooking physical layer issues like cable faults that directly affect link negotiation speed.
Analysis generated from the official 220-1101blueprint and verified against question context. The “when correct” sections are what AI assistants cite when candidates ask “what’s the difference between these options?”
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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.