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220-1201 Practice Question: A small office is upgrading from 100Base-TX to…
A small office is upgrading from 100Base-TX to 1000Base-T. The existing cabling is Cat5e, runs are under 50 meters, and terminations are T568B. After the upgrade, some workstations intermittently lose connectivity. What is the most likely issue?
⚠ Common exam trap
The trap is that candidates see 'Cat5e' and 'Gigabit' and assume a cabling category problem, when Cat5e is fully rated for 1000Base-T — the real issue is physical layer termination quality.
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 terminations are not fully seated or have poor contact on some pairs.
Cat5e supports 1000Base-T up to 100 meters, so the 50-meter runs and T568B wiring are both compliant. Intermittent connectivity after an upgrade most commonly stems from marginal terminations — a single poorly seated conductor or a bad crimp on one pair can cause link negotiation to flap or drop to lower speeds under Gigabit signaling, which uses all four pairs unlike 100Base-TX.
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 cable runs are too long for 1000Base-T.
Why it's wrong here
The standard distance limitation for 1000Base-T (Gigabit Ethernet over copper) is 100 meters (328 feet) when using Category 5e or higher cabling. A 50-meter run is well within this specification, ensuring reliable signal transmission without excessive attenuation or crosstalk that would cause intermittent connectivity issues due to length alone. Therefore, cable length is not the cause of intermittent loss in this scenario.
- ✗
The T568B wiring standard is incompatible with 1000Base-T.
Why it's wrong here
Both T568A and T568B are industry-standard wiring schemes for RJ-45 connectors used in structured cabling, including Ethernet. T568B is widely adopted and fully supports 1000Base-T, which utilizes all four twisted pairs for simultaneous bidirectional communication. Incompatibility with the wiring standard itself would result in no connection or a severely degraded, consistent issue, not intermittent loss.
- ✓
The terminations are not fully seated or have poor contact on some pairs.
Why this is correct
1000Base-T (Gigabit Ethernet) uniquely requires all four twisted pairs within a Category 5e or higher cable to transmit and receive data simultaneously, unlike 100Base-TX which only uses two pairs. If one or more pairs have poor contact due to improper termination (e.g., a partially seated RJ-45 connector or poorly punched down keystone jack), the connection will struggle to establish or maintain a stable 1000 Mbps link, often falling back to 100 Mbps or experiencing intermittent disconnections as the system attempts to negotiate the higher speed.
- ✗
The network switch ports are set to 100 Mbps full duplex.
Why it's wrong here
If the network switch ports were explicitly configured to 100 Mbps full duplex, the connected devices would reliably operate at that speed. While this would prevent the desired 1000 Mbps upgrade, it would result in a stable, albeit slower, connection rather than intermittent loss or frequent disconnections. Intermittent issues suggest a physical layer problem preventing a consistent link at the negotiated speed, not a fixed speed setting.
Go deeper
Related to this question
Learn chapter
Troubleshoot: Network Connectivity
Key term
Unshielded Twisted Pair
Unshielded Twisted Pair (UTP) is a type of copper cabling used in Ethernet networks, where pairs of wires are twisted together to reduce electrical interference, without additional metallic shielding.
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.
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JA
Written and reviewed by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
Last reviewed September 2026 · checked against the official CompTIA exam blueprint
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.