Fix Slow Network: Change Speed & Duplex from 10 Mbps Half to Auto-Negotiation
A user reports that their desktop computer is experiencing very slow network performance. The technician runs a speed test and gets only 10 Mbps download speed, while other devices on the same network achieve 500 Mbps. The technician checks the network adapter settings in the operating system and sees that 'Speed & Duplex' is manually set to '10 Mbps Half Duplex'. Which of the following should the technician do to resolve this issue?
Quick Answer
The answer is to change the Speed & Duplex setting from '10 Mbps Half Duplex' to 'Auto-Negotiation'. This is correct because manually locking the adapter to a fixed speed and duplex mode, such as 10 Mbps Half Duplex, prevents it from negotiating a higher link speed with the network switch, which is why the user experiences slow network speed due to manual speed duplex setting. On the CompTIA A+ Core 1 220-1101 exam, this scenario tests your understanding of how misconfigured NIC settings can bottleneck performance, and it often appears as a troubleshooting trap where a technician might overlook the adapter properties in favor of blaming the cable or router. A common memory tip is to remember that "Auto" is almost always the answer for speed and duplex issues, because modern switches and routers rely on automatic negotiation to establish the fastest stable connection. Think of it this way: if you force a manual setting, you’re telling the network card to ignore the highway and take a dirt road instead.
⚠ Common exam trap
A common mix-up: candidates think a slow network is always a cable or driver issue, but the CompTIA 220-1101 exam specifically tests the knowledge that manually setting Speed & Duplex overrides auto-negotiation and directly causes the reported symptom.
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
✓
Change the Speed & Duplex setting to 'Auto-Negotiation'
The issue is that the network adapter is manually locked to '10 Mbps Half Duplex', which forces a 10 Mbps connection even though the network infrastructure supports much higher speeds. Changing the setting to 'Auto-Negotiation' allows the adapter to automatically negotiate the highest mutually supported speed and duplex mode with the switch or router, restoring the expected 500 Mbps throughput.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
Replace the Ethernet cable with a Cat5e cable
Why it's wrong here
Cat5e cabling already supports gigabit speeds, so replacing it does not alter the adapter's forced 10 Mbps half-duplex setting, which is the actual bottleneck. Cable replacement is the right choice when physical damage or an inadequate category (such as Cat3) limits link negotiation, not when software duplex is pinned.
- ✗
Update the network adapter driver
Why it's wrong here
The driver is functioning, since the adapter negotiated a link and passed traffic at 10 Mbps; updating it leaves the manual speed and duplex setting unchanged. Driver updates are the correct choice for unstable connections, unrecognised hardware or repeated disconnects, not for a deliberately forced half-duplex configuration.
- ✓
Change the Speed & Duplex setting to 'Auto-Negotiation'
Why this is correct
The adapter is hard-coded to 10 Mbps half duplex, capping throughput and causing duplex mismatch with the switch. Setting Speed & Duplex to Auto-Negotiation lets the NIC negotiate 1 Gbps full duplex with the switch, restoring the 500 Mbps the other devices achieve.
- ✗
Disable and re-enable the network adapter
Why it's wrong here
Disabling and re-enabling the adapter only resets the link; the manually forced 10 Mbps half-duplex setting persists and continues capping throughput. It is tempting as a quick first-line fix for adapter faults, but it is the correct action when a NIC is unresponsive or has a hung driver, not when duplex is misconfigured.
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Same concept, more angles
1 more way this is tested on 220-1101
These questions test the same concept from different angles. Work through them to make sure you can recognise it however the exam phrases it.
Variation 1. 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?
medium- ✓ A.The Ethernet cable is damaged or of poor quality.
- B.The NIC driver is out of date.
- C.The switch port is configured for 10 Mbps full-duplex.
- D.The computer has a virus consuming bandwidth.
Why A: 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.
JA
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.