This XK0-005 practice question tests your understanding of troubleshooting. Read the scenario carefully and evaluate each option against the stated constraints before committing to an answer. 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.
A Linux server experiences intermittent network connectivity issues. The administrator suspects a duplex mismatch. Which tool can best confirm duplex and speed settings on a network interface?
Clue words in this question
Noticing these words before you look at the options changes how you read each choice.
Clue: "best"
Why it matters: Signals that multiple options may be partially correct. Choose the option that most directly solves the exact problem described, not the one that sounds most complete.
mii-tool eth0
Why wrong: mii-tool can show link status but is deprecated and less reliable for modern NICs.
dmesg | grep eth0
Why wrong: dmesg may contain driver messages but is not a direct tool for live settings.
ip link show eth0
Why wrong: ip link shows state and MTU but not duplex negotiation details.
ethtool eth0
ethtool shows detailed NIC settings including negotiated speed and duplex.
Answer choices
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
ethtool eth0
Option D is correct because `ethtool eth0` is the standard Linux utility for querying and controlling network interface driver and hardware settings, including negotiated speed and duplex mode. It directly displays the current link status, speed (e.g., 1000Mb/s), and duplex (full/half), making it the best tool to confirm a duplex mismatch.
Key principle: Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Answer analysis
For each option: why learners choose it and why it is or isn't the right answer here.
mii-tool eth0
Why it's wrong here
mii-tool can show link status but is deprecated and less reliable for modern NICs.
dmesg | grep eth0
Why it's wrong here
dmesg may contain driver messages but is not a direct tool for live settings.
ip link show eth0
Why it's wrong here
ip link shows state and MTU but not duplex negotiation details.
ethtool eth0
Why this is correct
ethtool shows detailed NIC settings including negotiated speed and duplex.
Clue confirmation
The clue word "best" in the question point toward this answer.
Related concept
Read the scenario before looking for a memorised answer.
Common exam traps
The trap here is that candidates confuse `ip link show` (which shows link state but not speed/duplex) with `ethtool` (which provides the actual negotiated parameters), leading them to pick option C because they think 'ip' is the modern replacement for all interface queries.
Trap categories for this question
Command / output trap
mii-tool can show link status but is deprecated and less reliable for modern NICs.
Detailed technical explanation
`ethtool` communicates with the NIC driver via ioctl calls to read the MII (Media Independent Interface) or Clause 45 registers, which store the auto-negotiated link parameters. A duplex mismatch occurs when one side is forced to full-duplex and the other auto-negotiates to half-duplex, causing frame collisions and CRC errors; `ethtool` can reveal this by showing 'Speed: 100Mb/s, Duplex: Half' on one side and 'Full' on the other. In real-world troubleshooting, `ethtool -S eth0` also exposes interface statistics like `collisions` and `rx_crc_errors` that corroborate a mismatch.
Key takeaway
Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Real-world example
A practitioner preparing for the XK0-005 exam encounters this exact type of scenario on the job. The correct answer here is not the most general option — it is the best answer for the specific constraint described. Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option. Real exam questions reward reading the full scenario before eliminating options, because the constraint defines which answer fits.
What to study next
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
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FAQ
Troubleshooting — This question tests Troubleshooting — Read the scenario before looking for a memorised answer..
The correct answer is: ethtool eth0 — Option D is correct because `ethtool eth0` is the standard Linux utility for querying and controlling network interface driver and hardware settings, including negotiated speed and duplex mode. It directly displays the current link status, speed (e.g., 1000Mb/s), and duplex (full/half), making it the best tool to confirm a duplex mismatch.
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
Yes — watch for: "best". Signals that multiple options may be partially correct. Choose the option that most directly solves the exact problem described, not the one that sounds most complete.
Read the scenario before looking for a memorised answer.
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Last reviewed: Jun 25, 2026
This XK0-005 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 XK0-005 exam.
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