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220-1201 Practice Question: A technician is deploying a new VoIP phone and…
A technician is deploying a new VoIP phone and needs to ensure the Ethernet cable connecting the phone to the wall jack provides sufficient power for the phone to operate. The network switch supports Power over Ethernet (PoE). Which tool can verify that PoE is active on the cable?
⚠ Common exam trap
Many exam-takers confuse a cable tester (which checks wiring) with a PoE tester (which checks power), leading them to select Option C because they think any 'tester' for cables will verify PoE, but only a dedicated PoE tester can confirm active power delivery.
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
✓
PoE tester
A PoE tester is specifically designed to detect the presence and voltage of Power over Ethernet on a cable, confirming that the switch is delivering power. Unlike a standard cable tester, it checks for the DC voltage (typically 48V) that powers the VoIP phone, ensuring the phone will operate without needing a separate power adapter.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
Multimeter
Why it's wrong here
While a multimeter can technically measure voltage, it is not the appropriate tool for quickly and safely detecting Power over Ethernet (PoE) on an RJ-45 jack. It would require precise knowledge of the specific PoE standard's pin assignments (e.g., Mode A or Mode B) and careful, manual probing of individual pins, which is impractical and carries a risk of shorting circuits or damaging equipment. This method is far less efficient and reliable than using a dedicated PoE tester.
- ✓
PoE tester
Why this is correct
A PoE tester is the most suitable and efficient tool for this task because it is specifically designed to detect and often identify the type of Power over Ethernet being supplied over an Ethernet cable. It safely connects inline or directly to the RJ-45 jack, providing clear indications of power presence, voltage levels, and sometimes even the PoE standard (e.g., 802.3af, 802.3at) and power mode (Mode A or Mode B). This ensures the VoIP phone receives adequate and compatible power for operation.
- ✗
Cable tester
Why it's wrong here
A standard cable tester's primary function is to verify the physical integrity and correct wiring of an Ethernet cable. It checks for continuity, open circuits, short circuits, and proper pinout (e.g., T568A or T568B), ensuring data can transmit reliably. However, it lacks the internal circuitry and sensors required to detect or measure the presence of electrical power, such as Power over Ethernet, on the data lines.
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Loopback plug
Why it's wrong here
A loopback plug is a diagnostic tool used to test the functionality of a network interface card (NIC) or a network port by sending data out and immediately receiving it back on the same interface. It verifies the transmit and receive capabilities of the hardware itself, confirming that the port is operational for data communication. This tool provides no information regarding the presence or absence of Power over Ethernet on the connected cable or port.
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Last reviewed: Jul 4, 2026
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