hardMultiple ChoiceObjective-mapped
220-1201 Practice Question: A customer reports that their new Cat6a…
A customer reports that their new Cat6a installation passes a cable certifier test but the link only negotiates at 100 Mbps. The cable run is 90 meters and uses standard T568B terminations. What is the most likely cause of the speed limitation?
⚠ Common exam trap
Candidates often assume a passing certifier result guarantees full link speed, but the certifier tests the permanent link only, not the patch cables, so the issue is likely in the patch cords.
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 patch cables are Cat5e instead of Cat6a.
The cable certifier passes because the physical layer (Cat6a cabling) meets specifications for signal integrity and crosstalk. However, if the patch cables connecting the equipment to the structured cabling are Cat5e, they may not support the higher frequencies required for 1000BASE-T (up to 100 MHz for Cat5e vs. 500 MHz for Cat6a). This can cause the link to fall back to 100BASE-TX, which operates at lower frequencies and is more tolerant of the reduced performance of Cat5e patch cables.
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 Cat6a.
Why it's wrong here
Cat6a cabling is specifically engineered to support 10 Gigabit Ethernet (10GBASE-T) over distances up to 100 meters (328 feet). If the cable run were, for instance, 90 meters, it would be well within this specified maximum length, ensuring full performance. A professional cable certifier, which the question states the installation "passes," would rigorously verify the cable's length and signal integrity against the Cat6a standard. Therefore, exceeding the maximum length is not the cause of a speed issue if the installation has already passed certification.
- ✗
The switch port is configured for 100 Mbps only.
Why it's wrong here
While a switch port misconfiguration could indeed limit a network connection to 100 Mbps, this scenario is less likely to be the primary issue when a new Cat6a installation has passed certification. A cable certifier tests the physical characteristics of the cable itself, such as wire map, attenuation, and crosstalk, ensuring it meets Cat6a standards for 10 Gbps. It does not test or validate active network device configurations, making a physical layer component mismatch a more direct explanation for a speed bottleneck after a successful cable test.
- ✓
The patch cables are Cat5e instead of Cat6a.
Why this is correct
Network performance is fundamentally dictated by the weakest link in the entire transmission chain. Even if the permanent Cat6a cabling infrastructure is certified for 10 Gigabit Ethernet, connecting devices with lower-grade Cat5e patch cables will create a significant bottleneck. Cat5e is typically rated for 1 Gigabit Ethernet (1000BASE-T) over its full length, and often only 100 Mbps (100BASE-TX) in certain scenarios or with degraded performance. This mismatch would limit the entire link's speed to the capabilities of the Cat5e patch cable, preventing the 10 Gbps potential of the Cat6a permanent link from being realized.
- ✗
The cable is terminated in T568A instead of T568B.
Why it's wrong here
Both T568A and T568B are valid wiring standards for Ethernet cabling, differing only in the pin-out order of the orange and green wire pairs. As long as both ends of a straight-through cable are terminated using the same standard (either T568A-to-T568A or T568B-to-T568B), the cable will function correctly and support its rated speed. A certifier test would detect any wire map errors, including a mixed termination (e.g., T568A on one end, T568B on the other), which would result in a failed test, not a speed reduction on an installation that has already passed.
Quick reference
OSI Model Reference
| Layer | Name | PDU | Key Protocols / Devices |
|---|---|---|---|
| 7 | Application | Data | HTTP, HTTPS, DNS, SMTP, FTP, SSH |
| 6 | Presentation | Data | TLS / SSL, JPEG, ASCII encoding |
| 5 | Session | Data | NetBIOS, RPC, SIP |
| 4 | Transport | Segment / Datagram | TCP, UDP |
| 3 | Network | Packet | IP, ICMP, OSPF — Routers |
| 2 | Data Link | Frame | Ethernet, Wi-Fi, PPP — Switches, Bridges |
| 1 | Physical | Bits | Cables, NICs, Hubs, Repeaters |
Go deeper
Related to this question
Learn chapter
Network Cable Types: Cat5e, Cat6, Cat6a, Cat8
Key term
Intermediate Distribution Frame
An Intermediate Distribution Frame (IDF) is a physical wiring closet or rack that connects and manages the cabling between a building's main telecommunications room and the end-user devices on a specific floor or area.
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 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.