220-1101 Hardware and Network Troubleshooting Practice Question
A technician is troubleshooting a desktop computer that connects to the network but experiences slow data transfers. The network uses a Gigabit Ethernet switch. The technician checks the network adapter status and sees that the link speed is 100 Mbps. The cable connecting the computer to the wall jack is a Cat5 cable. Which of the following is the MOST likely cause of the reduced speed?
⚠ Common exam trap
CompTIA often tests the distinction between Cat5 and Cat5e, where candidates mistakenly assume all Cat5 cables support Gigabit Ethernet because they physically fit the RJ45 port, ignoring the certification and performance standards.
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 cable is not certified for Gigabit Ethernet.
Cat5 cable is only certified for Fast Ethernet (100 Mbps) and does not meet the stricter specifications required for Gigabit Ethernet (1000 Mbps). While Cat5e or Cat6 cables are needed for reliable 1000BASE-T operation, a standard Cat5 cable will often force the link to negotiate down to 100 Mbps, causing the observed slow transfer speeds.
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 network adapter is configured for half-duplex.
Why it's wrong here
A half-duplex configuration means data can only travel in one direction at a time, which does reduce effective throughput. However, the link speed reported by the adapter is determined during autonegotiation based on the physical capabilities of the cable and ports, not by duplex mode. Even if the NIC were set to half-duplex, it would still negotiate 100 Mbps with a Cat5 cable; the category's frequency limit is what prevents a 1000 Mbps link.
- ✓
The cable is not certified for Gigabit Ethernet.
Why this is correct
Category 5 cabling is certified for 100BASE-TX (100 Mbps) and has a 100 MHz frequency rating. Gigabit Ethernet (1000BASE-T) requires all four twisted pairs to carry bidirectional signal and demands tighter specifications for return loss and crosstalk—standards that Cat5e and higher meet but original Cat5 does not. When a switch and NIC support gigabit but the cable is only Cat5, autonegotiation will fail to establish a 1000BASE-T link and fall back to the highest mutually supported speed, 100 Mbps.
- ✗
The switch port has been administratively disabled.
Why it's wrong here
An administratively disabled switch port is shut down at the configuration level, meaning it sends no frames and does not generate link pulses. From the computer's perspective, the network cable would appear unplugged: the link light would be off and the adapter would report 'network cable unplugged' or no connection at all. Since the user is connected at 100 Mbps, the port is definitely active, so this option cannot explain the symptom.
- ✗
The computer's operating system is outdated.
Why it's wrong here
An outdated operating system may cause poor performance or missing features, but the OS does not participate in physical-layer link negotiation. The link speed shown in the adapter status is the result of autonegotiation between network hardware and the cable's rated capability. A driver update could potentially fix a separate software issue, but it can never force a Cat5 cable to carry gigabit signals.
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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.