mediumMultiple ChoiceObjective-mapped
CS0-003 Practice Question: Based on the exhibit, which type of issue is most…
Exhibit
Refer to the exhibit. ``` ethtool -S eth0 | grep -E "(rx_crc_errors|rx_fifo_errors|rx_frame_errors)" rx_crc_errors: 2451 rx_fifo_errors: 12 rx_frame_errors: 892 ``` An analyst is investigating network performance issues on a Linux server. The exhibit shows output from ethtool.
Based on the exhibit, which type of issue is most likely affecting the server's network performance?
⚠ Common exam trap
CompTIA often tests the distinction between physical-layer errors (CRC, runts) and data-link layer issues (duplex mismatch, collisions), leading candidates to mistakenly choose duplex mismatch when the exhibit shows CRC errors instead of late collisions.
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
✓
Faulty network cable or interface
The exhibit shows excessive CRC errors and runts on the server's network interface, which are classic symptoms of a faulty physical layer component such as a damaged cable or failing NIC. These errors indicate that frames are being corrupted during transmission, and the interface is discarding them, leading to retransmissions and degraded performance. A faulty cable or interface directly causes these physical-layer issues, unlike configuration or driver problems.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✓
Faulty network cable or interface
Why this is correct
CRC (Cyclic Redundancy Check) errors and frame errors are strong indicators of data corruption occurring during transmission or reception. These typically point to issues at the physical layer (Layer 1) of the OSI model, such as a damaged Ethernet cable, a loose connection, or a malfunctioning network interface card (NIC) or switch port. Such physical defects introduce noise or signal degradation, leading to corrupted frames that fail their integrity checks upon arrival.
- ✗
Duplex mismatch between the server and switch
Why it's wrong here
A duplex mismatch occurs when one side of a link operates in full-duplex mode while the other operates in half-duplex. This scenario primarily leads to late collisions and alignment errors, as the half-duplex device attempts to transmit while the full-duplex device is also sending, causing data corruption due to simultaneous transmissions on a shared medium. While data corruption can occur, the primary symptoms are usually collisions and significant performance degradation, rather than high CRC errors alone.
- ✗
Incorrect TCP/IP configuration
Why it's wrong here
Incorrect TCP/IP configuration, such as a wrong IP address, subnet mask, or default gateway, affects network layer (Layer 3) and transport layer (Layer 4) communication. These issues would manifest as connectivity problems, routing failures, or inability to reach specific services, but they do not directly cause physical layer data corruption like CRC errors. CRC errors are a lower-layer issue related to the integrity of the transmitted frame itself.
- ✗
Outdated network driver
Why it's wrong here
An outdated or corrupted network driver can lead to various issues, including packet drops, intermittent connectivity, poor performance, or system instability. While a faulty driver could potentially misinterpret or misprocess frames, directly causing a high volume of CRC errors is less common. Driver issues are more likely to manifest as higher-level errors or system-level problems rather than consistent physical layer data integrity failures.
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Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
This CS0-004 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 CS0-004 exam.