JNCIS-ENT Layer 2 Switching And VLANs Practice Question
While reviewing the MAC address table on an EX Series switch using 'show ethernet-switching table', you notice a specific MAC address has a 'Flags' field showing 'L'. What does the 'L' flag indicate?
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 MAC address was learned locally/dynamically on the interface.
In Junos OS, the 'L' flag in the ethernet-switching table indicates that the MAC address was learned dynamically on that interface.
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 MAC address belongs to a local routed interface (VLAN interface IRB).
Why it's wrong here
Locally routed or static interface MACs have different flags, such as 'S' for static.
- ✓
The MAC address was learned locally/dynamically on the interface.
Why this is correct
Correct. 'L' stands for learned (dynamic learning).
- ✗
The MAC address has looped and triggered a storm control event.
Why it's wrong here
Loop detection flags or protocols handle loops; 'L' denotes dynamic MAC learning.
- ✗
The MAC address is locked and cannot move to another port.
Why it's wrong here
Locked MAC addresses use security features like port security, not the dynamic 'L' flag.
Quick reference
Access Control Model Comparison
| Model | Acronym | Who Controls Access? | Best For |
|---|---|---|---|
| Discretionary Access Control | DAC | Resource owner | Small teams, file shares |
| Mandatory Access Control | MAC | System / security labels | Classified govt / military |
| Role-Based Access Control | RBAC | Administrator (via roles) | Enterprise environments |
| Attribute-Based Access Control | ABAC | Policy engine (user + resource attributes) | Fine-grained, dynamic policies |
| Rule-Based Access Control | RuBAC | System rules / ACLs | Firewall rules, network ACLs |
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.