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220-1201 Practice Question: A user complains that their VoIP phone…
A user complains that their VoIP phone intermittently loses audio during calls. The phone is connected to a PoE switch. The technician checks the switch and sees that the port's PoE power budget is at 95% capacity. What is the most likely cause of the audio drops?
⚠ Common exam trap
CompTIA often tests the misconception that PoE power budget issues only cause devices to fail to power on, not intermittent behavior like audio drops during calls, leading candidates to incorrectly choose cable length or VLAN 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
✓
The switch is power-cycling the phone due to PoE power budget constraints.
When a PoE switch's power budget reaches 95% capacity, it may begin to prioritize power delivery, potentially power-cycling lower-priority devices like VoIP phones to free up power for critical devices. This intermittent power loss causes the audio drops, as the phone reboots or loses power momentarily. The issue is directly tied to PoE power management, not cable length, hardware faults, or VLAN 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.
- ✗
The Ethernet cable is too long, causing signal attenuation.
Why it's wrong here
Signal attenuation caused by an Ethernet cable exceeding its maximum length (typically 100 meters for copper) would generally lead to consistent and severe network performance degradation or complete loss of connectivity for all traffic. This issue would not typically manifest as intermittent audio drops specifically for a VoIP phone, nor would it cause the device to power cycle. Instead, it would result in constant packet loss or an inability to establish a stable link.
- ✗
The VoIP phone is faulty and needs replacement.
Why it's wrong here
While a faulty VoIP phone could indeed cause intermittent audio drops or other operational issues, this problem would typically be isolated to that specific device and not necessarily linked to the overall switch's power budget utilization. A device defect would not inherently trigger the switch to power-cycle the phone due to external power constraints. The intermittent nature, combined with the context of power, points away from a simple device failure.
- ✓
The switch is power-cycling the phone due to PoE power budget constraints.
Why this is correct
When a Power over Ethernet (PoE) switch's total power budget is exceeded or critically low, the switch's power management system may dynamically manage power distribution across its ports. This often involves temporarily cutting power to certain ports, especially those with lower priority or those drawing more power than allocated, to ensure critical devices remain operational. This power cycling causes the VoIP phone to reboot, leading directly to intermittent service interruptions and dropped calls.
- ✗
The switch port is configured with a VLAN mismatch.
Why it's wrong here
A VLAN mismatch between the switch port configuration and the VoIP phone's network settings would prevent the phone from establishing any network connectivity or registering with the call manager whatsoever. This would result in a complete and persistent failure to connect to the network, rather than intermittent audio drops or power cycling. The phone would likely display an error indicating no network or no registration.
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JA
Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
This 220-1201 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 220-1201 exam.