mediumMultiple ChoiceObjective-mapped
220-1201 Practice Question: During a network upgrade, a technician replaces…
During a network upgrade, a technician replaces an old 10/100 Mbps switch with a new gigabit switch. After the change, several users report that their internet connection is slow. The technician checks the switch and sees that some ports show 100 Mbps instead of 1000 Mbps. What is the most likely cause?
⚠ Common exam trap
A common misconception is that cable category (Cat5 vs. Cat5e) is the primary cause of speed negotiation failures, but in reality, the most common cause is the endpoint NIC's capability, as auto-negotiation will still attempt gigabit over Cat5 and only fall back if the cable fails or the NIC doesn't support it.
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 connected devices have 10/100 Mbps NICs
The most likely cause of the switch ports operating at 100 Mbps instead of 1000 Mbps is that the connected devices have 10/100 Mbps NICs. Gigabit Ethernet requires both the switch port and the connected device to support 1000BASE-T; if the NIC only supports 10/100, the switch will auto-negotiate down to the highest common speed, which is 100 Mbps. This explains why only some users experience slowness—those with older NICs are limited to 100 Mbps while others with gigabit-capable NICs get full speed.
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 switch ports are configured for half-duplex
Why it's wrong here
Half-duplex operation on an Ethernet link means data can only flow in one direction at a time, leading to increased collisions and retransmissions, severely degrading throughput. However, it does not inherently force a gigabit-capable link to negotiate down to 100 Mbps; the speed negotiation is a separate process from duplex settings. The symptom of a consistent 100 Mbps link points to a speed capability mismatch rather than a duplex misconfiguration.
- ✗
The Ethernet cables are Cat5 instead of Cat5e or Cat6
Why it's wrong here
While Cat5 cabling is officially rated for 100BASE-TX (100 Mbps), it can often support 1000BASE-T (Gigabit Ethernet) over shorter distances, typically up to 50 meters, especially if the cable quality is good. If a cable were truly inadequate for gigabit speeds, it would more likely result in an unstable link, frequent errors, or no link at all, rather than a consistent, stable negotiation down to 100 Mbps. The consistent 100 Mbps link suggests a limitation in the connected device's hardware capabilities, not solely the cable type.
- ✓
The connected devices have 10/100 Mbps NICs
Why this is correct
Ethernet devices utilize an auto-negotiation process to establish the highest common operating speed and duplex mode between two connected ports. If the network interface card (NIC) in a connected device is only capable of 10 Mbps or 100 Mbps, even when connected to a gigabit-capable switch port, the auto-negotiation will successfully establish a link at the maximum speed supported by the least capable device, which is 100 Mbps in this scenario. This directly explains the observed consistent 100 Mbps link speed.
- ✗
The switch has a faulty power supply causing reduced performance
Why it's wrong here
A faulty power supply in a network switch typically manifests as unstable operation, intermittent port failures, or a complete lack of power to the device. It would not generally cause a stable, consistent negotiation to a lower speed across functional ports. The symptom of a consistent 100 Mbps link points towards a compatibility or configuration issue with the connected devices, rather than a hardware failure affecting the switch's power delivery.
Go deeper
Related to this question
Learn chapter
Mobile Device Types and Features
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.
Key term
Ethernet
Ethernet is a wired networking technology that connects devices like computers, printers, and servers to each other and to the internet using cables.
About these practice questions
Courseiva writes every 220-1201 question from scratch — 972 in total, each with an explanation and a wrong-answer breakdown. None are copied from real exams or dumps. Learn why practice questions differ from exam dumps →
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.