JNCIS-ENT · domain
Layer 2 Switching And VLANs
This domain covers Layer 2 forwarding on Juniper EX Series switches running Junos OS: VLAN creation and membership, access and trunk port configuration, native VLAN and tagged/untagged frame handling, and the MAC address table. Questions are scenario-based, asking you to pick the correct configuration steps or interpret operational command output when troubleshooting connectivity.
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What this domain covers
What to know about Layer 2 Switching And VLANs
Be able to create a VLAN, assign a physical interface as an access port, and configure a trunk with correct tagged and native VLAN handling on EX Series switches. The single most important thing: match interface mode and VLAN membership so frames are forwarded in the intended VLAN.
Why learners struggle
Why Layer 2 Switching And VLANs 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 Layer 2 Switching And VLANs exam traps
- ▸Forgetting to set the interface mode to access before adding the VLAN membership, so the port stays in the default mode.
- ▸Assuming a trunk carries untagged traffic without configuring native-vlan-id, causing untagged frames to be dropped or mishandled.
- ▸Confusing 'show ethernet-switching table' with 'show bridge mac-table' and misreading which VLAN or interface a MAC was learned on.
Question index
All Layer 2 Switching And VLANs questions (20)
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An enterprise network design requires implementing private VLANs (PVLANs) on an EX Series switch. Which THREE components or port types are characteristic of a private VLAN architecture? (Choose three.)
Hard2You are reviewing the configuration of an EX Series switch and notice that interface ge-0/0/15 is configured with 'interface-mode access' but has no explicit 'vlan members' statement defined. Which VLAN does the interface default to?
Medium3An administrator needs to view the MAC address learning table on an EX Series switch to verify which switchport a specific server is connected to. Which operational command should be used?
Easy4You are configuring a Private VLAN (PVLAN) on an EX Series switch to isolate hosts within a DMZ segment while allowing them to reach a shared gateway. Which TWO statements correctly describe the behavior of PVLAN port types in this scenario? (Choose two.)
Medium5When configuring Private VLANs (PVLANs) on Juniper EX Series switches, which TWO types of ports are defined within the architecture? (Choose two.)
Hard6An administrator configures a new VLAN ID 300 on an EX Series switch but forgets to assign any interfaces to it. What is the operational status of this VLAN?
Easy7An enterprise network uses private VLANs. A server connected to an isolated port needs to send traffic out of the primary VLAN. Which statement accurately describes how traffic forwarding operates for an isolated port in Junos?
Hard8An administrator runs 'show vlans' and notices that a particular VLAN has the status 'Active' but no interfaces listed under it. What does this indicate?
Easy9An operator executes the command 'show bridge mac-table' on an EX Series switch running Junos OS. Which information is displayed in the output of this command?
Easy10An engineer is deploying Private VLANs on an EX Series switch and needs to verify proper operational status and traffic isolation. Which THREE tasks or verification checks should be performed? (Choose three.)
Hard11An administrator needs to delete an entire VLAN configuration named 'guest' along with its VLAN ID and associated properties. Which configuration command should be executed?
Easy12Which THREE parameters are typically verified when troubleshooting a missing MAC address entry in the bridge table of a Juniper switch? (Choose three.)
Medium13You are troubleshooting a Layer 2 connectivity problem where a trunk port is dropping tagged traffic for VLAN 50. Which TWO configuration checks should be performed? (Choose two.)
Medium14An administrator is configuring VLANs on a Junos EX Series switch. Which TWO tasks must be performed to successfully assign a physical interface as an access port for a newly created VLAN? (Choose two.)
Easy15An administrator is configuring a new EX Series switch running Junos OS and needs to assign an access port to VLAN finance. Which configuration hierarchy is used to assign an interface to a specific VLAN?
Easy16You are troubleshooting a connectivity issue between an EX4300 switch access port and an end-host. The port is configured as an access port for VLAN 100, but the host cannot communicate. You run 'show ethernet-switching interface ge-0/0/1' and notice the port status is down/down. Which underlying reason most likely explains this state?
Medium17An engineer is configuring a trunk port on an EX Series switch and needs to ensure that untagged and priority-tagged frames are handled correctly. Which TWO configuration actions are required? (Choose two.)
Medium18An EX4300 switch is configured with a trunk port that carries VLAN 10 and VLAN 20. The trunk is connected to a third-party switch that uses a native VLAN of 1 for untagged traffic. You notice that untagged frames from the third-party switch are being dropped on the EX4300. Which configuration change resolves this issue?
Hard19An administrator needs to create a VLAN named 'voice' with a VLAN ID of 50 on a Junos EX Series switch. Which configuration path achieves this?
Easy20An administrator is configuring Selective QinQ on an EX Series switch using VLAN translation. Which THREE components are required to successfully rewrite inner and outer VLAN tags? (Choose three.)
HardOther domains
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Frequently asked questions
- What does the Layer 2 Switching And VLANs domain cover on the JNCIS-ENT exam?
- Be able to create a VLAN, assign a physical interface as an access port, and configure a trunk with correct tagged and native VLAN handling on EX Series switches. The single most important thing: match interface mode and VLAN membership so frames are forwarded in the intended VLAN.
- How many questions are in this domain?
- This page lists all 20 Layer 2 Switching And VLANs questions in the JNCIS-ENT question bank. The actual exam draws from this domain proportionally to its weighting in the official exam blueprint.
- What is the best way to practise this domain?
- Start with a short focused session (10 questions) to identify gaps, then work through explanations. Repeat with a longer session once the weak areas feel solid.
- Can I practise only Layer 2 Switching And VLANs questions?
- Yes — the session launcher on this page filters questions to this domain only. Choose any session length for inline explanations and scoring.