mediumMultiple ChoiceObjective-mapped
220-1201 STP (Shielded Twisted Pair) Practice Question
A customer reports that their new Gigabit Ethernet connection is only achieving 100 Mbps speeds. The cable run is about 75 meters through a drop ceiling. The technician checks the patch panel and wall jack terminations, which appear correct. What is the most likely cause of the speed issue?
⚠ Common exam trap
Do not assume that a speed downgrade is always due to cable category; shielding mismatches and faulty pairs are common causes.
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 shielded (STP) and the connectors are unshielded (UTP).
The most likely cause is that the cable is shielded (STP) but the connectors are unshielded (UTP). When STP cable is used with UTP connectors, the shielding is not properly grounded, leading to signal interference and degradation. This often results in the link falling back to 100 Mbps. The 75-meter run is within the 100-meter limit for Gigabit, and terminations appear correct, so the shield mismatch is the primary suspect.
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 run exceeds the maximum length for Gigabit Ethernet.
Why it's wrong here
Standard specifications for Gigabit Ethernet (1000BASE-T) over twisted-pair copper cabling, as defined by IEEE 802.3ab, establish a maximum segment length of 100 meters (approximately 328 feet). The reported cable run of 75 meters falls well within this specified limit. Therefore, the cable's length is not exceeding the maximum allowable distance and cannot be the cause of the speed reduction to 100 Mbps.
- ✗
The cable is Cat5 or lower, which cannot support Gigabit Ethernet at that distance.
Why it's wrong here
While older Category 5 (Cat5) cabling is generally not certified for reliable Gigabit Ethernet (1000BASE-T) performance, especially over longer distances, Category 5e (Cat5e) cable is specifically designed and rated to support 1000BASE-T up to its full 100-meter length. Since the option broadly states 'Cat5 or lower,' and Cat5e is fully capable of Gigabit speeds at 75 meters, this statement is not a universally correct explanation for the observed speed downgrade.
- ✗
The wall jack is wired for T568B but the patch panel uses T568A.
Why it's wrong here
A mismatch between T568A and T568B wiring standards at opposing ends of a straight-through cable run would result in incorrect pin assignments for the transmit and receive pairs. This typically leads to a complete failure to establish a link, or severe, intermittent connectivity issues with high error rates, as the network devices cannot properly communicate. It is highly unlikely to result in a stable, consistent downgrade to 100 Mbps, which requires a functional, albeit slower, connection.
- ✓
The cable is shielded (STP) and the connectors are unshielded (UTP).
Why this is correct
Shielded Twisted Pair (STP) cables rely on their metallic shield to protect against electromagnetic interference (EMI) and radio frequency interference (RFI). For this shield to be effective, it must be properly grounded, typically through shielded connectors. Using unshielded (UTP) connectors with an STP cable prevents the shield from being correctly terminated and grounded, rendering it ineffective. This increased susceptibility to noise can degrade signal quality, forcing the network interface card (NIC) to negotiate down to a more robust, slower speed like 100 Mbps.
Visual reference
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Related to this question
Learn chapter
Internet Connection Types
Key term
Bridge Protocol Data Unit
A Bridge Protocol Data Unit (BPDU) is a special message that network switches exchange to detect and prevent loops in an Ethernet network.
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.
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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.