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JNCIP-ENT · topic practice

Ethernet Switching And Spanning Tree practice questions

This domain covers Ethernet switching on Juniper EX and MX platforms: VLANs, Q-in-Q and vlan-map, MSTP/RSTP/VSTP, and Layer 2 features like voice VLAN. Questions are scenario-based, asking you to pick the correct Junos configuration stanza or identify which parameters must match for a feature to work.

Courseiva uses original exam-style practice questions designed for learning and revision. The goal is to understand the concepts, recognise exam patterns, and improve through explanations — not memorise copied exam dumps.

Editorial oversight:Johnson Ajibi· MSc IT Security, IEEE Senior Member
20 questionsDomain: Ethernet Switching And Spanning Tree
Practice 10 questionsBrowse domain →

What the exam tests

What to know about Ethernet Switching And Spanning Tree

Be able to write and read Junos VLAN, Q-in-Q, and MSTP configuration on EX and MX, and state exactly which parameters must match for MSTP regions and which knobs push or swap outer tags. Getting MSTP region matching right is the single most important point.

Q-in-Q tunneling with vlan-map to push an outer service provider VLAN tag

MSTP region membership: region name, revision level, and VLAN-to-instance mapping

Voice VLAN configuration on EX switches using LLDP-MED to place phone traffic

Transparent tunneling of customer STP BPDUs across a provider bridge core

Why learners struggle

Why Ethernet Switching And Spanning Tree questions are commonly missed

Common Networking Hardware questions are often missed because learners confuse device functions and port types. The exam tests specific hardware features like PoE and managed switching that are easy to mix up.

  • ·Router vs switch — routing vs switching function
  • ·PoE vs PoE+ — power budget differences
  • ·Managed vs unmanaged — configuration capability
  • ·Access point vs router — wireless vs routing
  • ·Patch panel vs switch — termination vs active
  • ·Cat5e vs Cat6 — speed and frequency limits

Watch out for

Common Ethernet Switching And Spanning Tree exam traps

  • ▸Assuming MSTP switches form one region by protocol alone; region name, revision, and VLAN mapping must all match.
  • ▸Confusing vlan-map direction or placement on MX, so the outer tag is pushed or swapped incorrectly.
  • ▸Forgetting that voice VLAN relies on LLDP-MED or an OUI so the phone tags its own traffic.

Practice set

Ethernet Switching And Spanning Tree questions

20 questions · select your answer, then reveal the explanation

Question 1easymultiple choice
Open the full VLAN trunking answer →

You are configuring VSTP (VLAN Spanning Tree Protocol) on Juniper EX switches to interoperate with legacy third-party switches running PVST+. Which operational command allows you to verify the VSTP bridge identifier and root bridge status per VLAN?

Question 2mediummultiple choice
Open the full VLAN trunking answer →

You are reviewing the MSTP configuration on an EX4300 switch. You want to assign VLANs 10 through 50 to Multiple Spanning Tree Instance (MSTI) 2. Which syntax under 'protocols mstp' is correct?

Question 3mediummultiple choice
Open the full STP breakdown →

An enterprise network uses VSTP. During a topology change, network administrators notice excessive flooding of broadcast traffic. Which Juniper configuration statement under 'protocols vstp' prevents unnecessary topology change flooding by restricting TCN propagation?

Question 4mediummultiple choice
Open the full VLAN trunking answer →

You are troubleshooting a Q-in-Q tunneling implementation on an MX Series router where customer VLAN tags are being stripped instead of preserved across the service provider core. Under which configuration hierarchy should the 'vlan-tagging' and 'pop-pop' or 'push' actions be applied on the interface?

Question 5easymultiple choice
Open the full VLAN trunking answer →

An enterprise network engineer needs to configure a trunk port on a Juniper EX Series switch running Junos OS to allow multiple VLANs while explicitly blocking VLAN 99. Which configuration statement under 'interfaces ge-0/0/1 unit 0 family ethernet-switching' correctly achieves this?

Question 6easymultiple choice
Open the full STP breakdown →

An administrator needs to enable BPDU protection on edge access ports in a VSTP environment to prevent loops caused by unauthorized switches. Which command under 'protocols vstp' accomplishes this globally or per-interface?

Question 7hardmultiple choice
Open the full STP breakdown →

An enterprise network runs MSTP across an EX Series core. An administrator wants to ensure that a specific core port never becomes the root port for any MSTI, protecting the upstream core path. Which command achieves this?

Question 8mediummultiple choice
Open the full VLAN trunking answer →

You are configuring selective Q-in-Q stacking on an MX Series router. Unlike standard Q-in-Q where all customer VLANs are encapsulated into a single provider VLAN, selective Q-in-Q allows you to map specific customer VLAN ranges to different provider VLANs. Which configuration element enables this granularity?

Question 9hardmultiple choice
Open the full VLAN trunking answer →

An enterprise network operates VSTP across 150 VLANs. The network engineering team notices high CPU utilization on the Routing Engine due to VSTP BPDU processing. Which Junos command or feature can mitigate this control-plane load while keeping VSTP operational?

Question 10easymultiple choice
Open the full STP breakdown →

An administrator needs to configure a port on an EX series switch to act as a Designated Port in MSTP, forcing it to forward traffic regardless of incoming superior BPDUs from an untrusted switch. Which feature should be enabled on this port?

Question 11easymultiple choice
Open the full STP breakdown →

You are troubleshooting MAC address learning on an EX Series switch and want to display dynamic MAC entries learned specifically on interface ge-0/0/5. Which operational command should you use?

Question 12mediummultiple choice
Open the full VLAN trunking answer →

You are configuring a Juniper EX Series switch to participate in an existing VSTP domain. You notice that certain VLANs are not participating in VSTP and are dropping traffic. What is the default behavior of VSTP on a newly created VLAN in Junos?

Question 13easymultiple choice
Open the full STP breakdown →

An administrator needs to verify the operational state of an MSTP instance named 'MSTI-1' on an EX Series switch, including its designated root and regional parameters. Which operational command should be executed?

Question 14hardmultiple choice
Open the full STP breakdown →

In a Juniper Q-in-Q deployment, customer frames are received with an EtherType of 0x8100 (IEEE 802.1Q). The service provider network uses a custom provider EtherType of 0x9100 for outer tags. Where and how is this custom EtherType configured on an MX Series router?

Question 15mediummulti select
Open the full STP breakdown →

Which TWO configuration statements are required when setting up an MSTP region on a Juniper EX Series switch? (Choose two)

Question 16hardmulti select
Open the full STP breakdown →

Which THREE mechanisms are provided by Juniper switches running MSTP to protect against bridging loops caused by unidirectional link failures or misbehaving switches? (Choose three)

Question 17hardmulti select
Open the full STP breakdown →

When designing a high-scale enterprise campus network using Juniper EX Series switches, which THREE best practices should be followed for Spanning Tree Protocol design? (Choose three)

Question 18mediummultiple choice
Open the full VLAN trunking answer →

An engineer is configuring QinQ (802.1ad) tunneling on a Juniper EX Series switch to transport customer VLANs across a service provider core. The customer-facing access port receives tagged frames with outer VLAN ID 100 and inner VLAN ID 200. Which configuration statement correctly defines the interface encapsulation and VLAN mapping?

Question 19hardmultiple choice
Open the full VLAN trunking answer →

An enterprise network running VSTP (VLAN Spanning Tree Protocol) across Juniper EX Series switches experiences unexpected loops because a newly added switch does not participate in VSTP for VLAN 50. Upon investigation, you discover the VSTP BPDU multicast destination MAC address is being dropped by a third-party non-Juniper intermediate switch. What is the standard VSTP MAC address used for BPDU transmission?

Question 20hardmultiple choice
Open the full VLAN trunking answer →

When designing large-scale Layer 2 networks using VSTP, you notice high CPU utilization on the Routing Engine due to the large number of topology changes and BPDU processing across 150 VLANs. Which command can you apply globally or per-interface in Junos to optimize VSTP performance and mitigate CPU load?

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Frequently asked questions

What does the JNCIP-ENT exam test about Ethernet Switching And Spanning Tree?
Be able to write and read Junos VLAN, Q-in-Q, and MSTP configuration on EX and MX, and state exactly which parameters must match for MSTP regions and which knobs push or swap outer tags. Getting MSTP region matching right is the single most important point.
How should I use these practice questions?
Select your answer before revealing the explanation. Then read why each option is right or wrong — this active recall approach builds retention far faster than re-reading notes.
Can I practise just Ethernet Switching And Spanning Tree questions in a focused session?
Yes — the session launcher on this page draws every question from the Ethernet Switching And Spanning Tree domain. Use a 10-question session first to gauge your baseline, then move to 20 or 30 once the weak spots are clear.
Where can I practise other JNCIP-ENT topics?
Use the topic links above to move to related areas, or go back to the JNCIP-ENT question bank to see all topics.
Are these real exam questions or dumps?
These are original practice questions written to test the same concepts the JNCIP-ENT exam covers. They are not copied from any real exam or dump site.