JNCIP-ENT Practice Question: You notice that an EX4300 switch power budget calculation is set to use 'class-based'…
You notice that an EX4300 switch power budget calculation is set to use 'class-based' allocation. What does this mean regarding how power is reserved for connected IP phones?
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 reserves power according to the maximum wattage defined by the device's hardware PoE class (e.g., Class 0, Class 3).
Class-based power allocation reserves the maximum wattage specified by the device's 802.3af/at power class, regardless of actual consumption.
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 switch allocates a flat 15.4W to every port regardless of what device is plugged in.
Why it's wrong here
Reserving a fixed 15.4 W per port regardless of the connected device describes static allocation, where the switch reserves the configured maximum for each port. Class-based allocation instead reserves the maximum for the class each device reports: 4 W for Class 1, 7 W for Class 2, 15.4 W for Classes 0 and 3, and 30 W for Class 4 under 802.3at.
- ✓
The switch reserves power according to the maximum wattage defined by the device's hardware PoE class (e.g., Class 0, Class 3).
Why this is correct
In class-based mode, the switch reserves power for each device according to the PoE class it reports during detection and classification, using the class maximum rather than actual consumption. That makes the budget predictable, but it can leave unused headroom, because many phones in Class 3 draw much less than 15.4 W. 'show poe controller' shows the mode, total budget and power in use.
- ✗
The switch shares a dynamic pool where ports draw power on a first-come, first-served basis without limits.
Why it's wrong here
No PoE management mode lets ports draw power without limits, because exceeding the power supply's budget would cause ports, or the switch, to lose power unpredictably. When the budget is exhausted, Junos powers ports by priority, keeping high-priority ports powered first. Class-based mode reserves a defined amount for each device according to its PoE class.
- ✗
The switch allocates power based on real-time LLDP-MED reported consumption values.
Why it's wrong here
Allocating power from what devices report through LLDP-MED, or from measured consumption, is a different approach that refines allocation using the device's actual needs. Class-based mode does not use live readings; it reserves the maximum for the device's class. LLDP power negotiation can make better use of the budget, which is why it exists as a separate capability.
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Written and reviewed by Johnson Ajibi, MSc IT Security
Security Systems Architect · founder of Courseiva
Last reviewed August 2026 · checked against the official Juniper Networks exam blueprint
This JNCIP-ENT practice question is part of Courseiva's free Juniper Networks 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 JNCIP-ENT exam.