JNCIS-ENT Layer 2 Security Practice Question
An administrator configures a Layer 2 firewall filter to drop all ARP packets with a specific invalid sender hardware address. The filter is applied to a VLAN interface. What special consideration must be taken when applying Layer 2 filters to VLANs in Junos?
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
✓
Layer 2 filters on VLANs evaluate traffic across all member ports belonging to that VLAN instance.
Layer 2 firewall filters applied to VLANs filter traffic across all member ports of that VLAN and must be defined using family ethernet-switching.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
Layer 2 filters applied to VLANs require family inet to inspect ARP payloads.
Why it's wrong here
ARP uses family ethernet-switching for L2 filtering, not family inet.
- ✓
Layer 2 filters on VLANs evaluate traffic across all member ports belonging to that VLAN instance.
Why this is correct
Applying a Layer 2 filter to a VLAN affects all ingress traffic on all physical ports associated with that VLAN.
- ✗
Layer 2 filters cannot be applied to VLANs; they must be applied to physical interfaces only.
Why it's wrong here
Layer 2 filters can be applied to both physical interfaces and VLANs in Junos.
- ✗
VLAN-based Layer 2 filters only process egress traffic leaving the VLAN trunk ports.
Why it's wrong here
L2 filters applied to VLANs process ingress traffic entering the VLAN bridge domain.
Visual reference
About these practice questions
Courseiva writes every JNCIS-ENT question from scratch — 506 in total, each with an explanation and a wrong-answer breakdown. None are copied from real exams or dumps. Learn why practice questions differ from exam dumps →
JA
Written and reviewed by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
Last reviewed August 2026 · checked against the official Juniper Networks exam blueprint
This JNCIS-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 JNCIS-ENT exam.