20+ practice questions focused on Spanning Tree — one of the most tested topics on the Juniper Networks Enterprise Routing and Switching, Specialist (JNCIS-ENT, JN0-352) (JNCIS-ENT) exam. Each question includes a detailed explanation so you learn why the right answer is correct.
Start Spanning Tree PracticeWhich command allows an operator to view the designated root bridge identifier and port roles for all active VLANs under RSTP?
Explanation: The command 'show spanning-tree bridge' displays the designated root bridge identifier and port roles for all active VLANs under RSTP. It provides a summary of the spanning tree topology, including the root bridge ID, root path cost, and port roles for each VLAN. This is the correct command to view the root bridge and port roles.
An EX Series switch running RSTP receives BPDUs with superior path cost information from an unauthorized access switch. Which feature should you enable on access-facing ports to prevent these unauthorized BPDUs from altering the spanning tree topology?
Explanation: BPDU guard is the correct feature to enable on access-facing ports to prevent unauthorized BPDUs from altering the spanning tree topology. When BPDU guard is enabled on an interface, the port is shut down (err-disabled) if it receives a BPDU, which stops an unauthorized switch from participating in STP. This is the standard defense against rogue switches on access ports.
You are troubleshooting a suboptimal spanning tree topology where an EX4300 switch is chosen as the STP Root Bridge despite having a high bridge priority. What command helps verify the current bridge priority and local bridge identifier parameters?
Explanation: The 'show spanning-tree bridge' command on Junos EX switches displays the local bridge identifier, bridge priority, and related STP parameters for the switch. This directly answers the question of verifying the current bridge priority and local bridge ID when troubleshooting root bridge election.
An administrator has deployed a new EX Series switch running RSTP and notices that access ports connected to end-user workstations take up to 30 seconds to transition to the forwarding state. Which configuration command should be applied to immediately resolve this delay for access ports?
Explanation: RSTP (802.1w) still uses the original 802.1D timers (Listening/Learning) on ports that are not explicitly identified as edge ports, which is why the access port waits ~30 seconds. Configuring 'set protocols rstp interface ge-0/0/1.0 edge' tells RSTP that no BPDUs will ever be received on that port, so it can transition directly to forwarding (like PortFast in Cisco). This is the correct, targeted fix for end-user access ports.
You are configuring MSTP and want to assign VLANs 10 through 50 to MST instance 2. Which configuration hierarchy is correct in Junos OS?
Explanation: In Junos OS, MSTP configuration is done under the [edit protocols mstp] hierarchy. To assign VLANs to an MST instance, you use the 'instance' statement with a name (e.g., msti2) and then specify the VLANs using 'vlan 10-50'. The correct syntax is 'set protocols mstp configuration-name RegionA revision 1 instance msti2 vlan 10-50'. This creates an MST instance named msti2 and maps VLANs 10 through 50 to it.
+15 more Spanning Tree questions available
Practice all Spanning Tree questions1. Baseline your knowledge
Start with 10 questions to gauge your current understanding of Spanning Tree. This tells you whether you need a concept refresher or just practice.
2. Review every explanation
For each question — right or wrong — read the full explanation. Understanding why an answer is correct is more valuable than knowing the answer itself.
3. Focus on exam traps
Spanning Tree questions on the JNCIS-ENT frequently use trap wording. Look for subtle differences in answers that test your precision, not just general knowledge.
4. Reach 80% consistently
Do repeated sessions until you score 80%+ three times in a row. Then move to mixed-mode practice to test cross-topic recall under realistic conditions.
The exact number varies per candidate. Spanning Tree is tested as part of the Juniper Networks Enterprise Routing and Switching, Specialist (JNCIS-ENT, JN0-352) (JNCIS-ENT) blueprint. Practicing with targeted Spanning Tree questions ensures you can handle any format or difficulty that appears.
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Difficulty is subjective, but Spanning Tree is a high-priority exam concept tested in multiple ways — direct recall, scenario analysis, and command-output interpretation. Consistent practice is the best way to build confidence.
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