350-401 Network Assurance Practice Question
A network administrator is troubleshooting a network performance issue and suspects a duplex mismatch on a switch port. Which command should be used to verify the duplex settings on a Cisco switch interface?
⚠ Common exam trap
The trap here is relying on the running configuration, which only shows configured duplex and not the actual operational duplex, potentially missing a mismatch.
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
✓
show interfaces GigabitEthernet0/1
The show interfaces command provides comprehensive details about an interface, including duplex mode, speed, and error statistics. It shows both the configured duplex and the operational duplex, which is essential for detecting a mismatch. When a duplex mismatch occurs, the interface may show late collisions and other errors. The other commands either lack detail or do not show operational duplex.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✓
show interfaces GigabitEthernet0/1
Why this is correct
The show interfaces GigabitEthernet0/1 command displays detailed information about the specified interface, including the configured and operational duplex mode. This is the correct command to verify duplex settings, as it shows both the hardware and configured duplex, and can indicate mismatches.
- ✗
show running-config interface GigabitEthernet0/1
Why it's wrong here
This command displays the configuration of the interface, including duplex settings if explicitly configured. However, it does not show the operational duplex or detect mismatches. It only shows what is configured, not what is currently in effect, so it may not reveal a duplex mismatch.
- ✗
show interfaces status
Why it's wrong here
The show interfaces status command provides a summary of all interfaces, including status, VLAN, duplex, and speed. However, it may not show detailed duplex information for all interface types, and it does not provide the configured duplex settings. It is useful for a quick overview but not for in-depth duplex verification.
- ✗
show controllers GigabitEthernet0/1
Why it's wrong here
The show controllers command displays low-level hardware statistics and is primarily used for troubleshooting physical layer issues. It does not typically show duplex settings. It is not the appropriate command for verifying duplex configuration or operational status.
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Written and reviewed by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
Last reviewed September 2026 · checked against the official Cisco exam blueprint
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