XK0-006 Troubleshooting Practice Question
A Linux server is experiencing intermittent network connectivity issues. The administrator suspects that the network interface is dropping packets due to a duplex mismatch. Which command should be used to check the duplex setting and link status of the interface?
⚠ Common exam trap
The trap here is assuming that basic interface commands like ifconfig or ip link show duplex settings; they do not, so ethtool is required.
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
✓
ethtool eth0
The ethtool command is the standard tool for querying and modifying Ethernet device settings, including duplex and speed. It directly reports the negotiated duplex mode, allowing the administrator to verify if the interface is operating at half duplex when it should be full duplex. Other commands like ifconfig or ip link do not expose duplex information, and netstat only shows statistics, not configuration.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
ifconfig eth0
Why it's wrong here
ifconfig displays IP address, netmask, and basic interface statistics such as packets received and transmitted, but it does not report duplex settings or link speed. It cannot reveal a duplex mismatch because that information is not part of its output. Thus, it is insufficient for diagnosing this specific hardware-level issue.
- ✗
ip link show eth0
Why it's wrong here
ip link show eth0 shows the link-layer information such as MAC address, MTU, and operational state (UP/DOWN), but it does not include duplex or speed details. While it can confirm if the interface is up, it does not provide the duplex setting, so it cannot help identify a duplex mismatch causing packet drops.
- ✗
netstat -i
Why it's wrong here
netstat -i displays interface statistics including packet errors and collisions, which might hint at a duplex mismatch, but it does not directly show the duplex setting. It provides cumulative counters rather than current configuration. Therefore, it cannot definitively confirm the duplex mode of the interface.
- ✓
ethtool eth0
Why this is correct
The ethtool command queries and controls network driver and hardware settings. Running ethtool eth0 displays the link status, speed, duplex mode, and other low-level parameters. It directly shows whether the interface is running at full or half duplex, which is critical for diagnosing a duplex mismatch that can cause packet loss and intermittent connectivity.
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JA
Written and reviewed by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
Last reviewed September 2026 · checked against the official CompTIA exam blueprint
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