This CS0-003 practice question tests your understanding of security operations. The scenario asks you to isolate a root cause — eliminate options that address a different problem before choosing. After answering, compare your reasoning against the explanation and wrong-answer breakdown below. Once you have made your selection, read the full explanation to reinforce the concept and understand why each distractor is designed to mislead on exam day.
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?
Clue words in this question
Noticing these words before you look at the options changes how you read each choice.
Clue: "most likely"
Why it matters: Probability qualifier — the question wants the most probable cause or outcome, not a guaranteed one. Eliminate low-probability options.
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.
A
Faulty network cable or interface
High CRC and frame errors suggest physical layer problems.
B
Duplex mismatch between the server and switch
Why wrong: Duplex mismatch typically causes collisions and alignment errors, not necessarily CRC errors.
C
Incorrect TCP/IP configuration
Why wrong: Configuration issues would not cause CRC errors.
D
Outdated network driver
Why wrong: Driver issues may cause different errors like drops or timeouts.
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.
Key principle: Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
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
High CRC and frame errors suggest physical layer problems.
Clue confirmation
The clue word "most likely" in the question point toward this answer.
Related concept
Read the scenario before looking for a memorised answer.
✗
Duplex mismatch between the server and switch
Why it's wrong here
Duplex mismatch typically causes collisions and alignment errors, not necessarily CRC errors.
✗
Incorrect TCP/IP configuration
Why it's wrong here
Configuration issues would not cause CRC errors.
✗
Outdated network driver
Why it's wrong here
Driver issues may cause different errors like drops or timeouts.
Common exam traps
Common exam trap: answer the scenario, not the keyword
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.
Detailed technical explanation
How to think about this question
CRC errors occur when the Ethernet frame's cyclic redundancy check fails, indicating bit corruption during transmission, often due to electrical interference, damaged cabling, or a failing transceiver. Runts are frames smaller than the minimum 64 bytes (excluding preamble) and can result from collisions or faulty hardware that truncates packets. In a real-world scenario, a bent pin in an RJ45 connector or a cable exceeding the 100-meter limit for twisted-pair Ethernet can cause these errors, and tools like `ethtool -S` on Linux or `netstat -e` on Windows can reveal the specific error counters.
KKey Concepts to Remember
Read the scenario before looking for a memorised answer.
Find the constraint that changes the correct option.
Eliminate answers that are true in general but not in this case.
TExam Day Tips
→Watch for words such as best, first, most likely and least administrative effort.
→Review why wrong options are wrong, not only why the correct option is correct.
Key takeaway
Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Real-world example
How this comes up in practice
A security analyst at a medium-sized enterprise encounters this scenario during an investigation or architecture review. The correct answer reflects best practice for the specific threat or control described. Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option. Security exam questions test whether you can match controls to threats in context — not just recall definitions.
Related glossary terms
Concepts from this question explained
These glossary pages explain the core terms tested in this CS0-003 question in full detail.
Security Operations — This question tests Security Operations — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: 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.
What should I do if I get this CS0-003 question wrong?
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
Are there clue words in this question I should notice?
Yes — watch for: "most likely". Probability qualifier — the question wants the most probable cause or outcome, not a guaranteed one. Eliminate low-probability options.
What is the key concept behind this question?
Read the scenario before looking for a memorised answer.
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Question Discussion
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