JNCIP-ENT IP Telephony Features Practice Test 2 — 15 Questions

Question 1

An IP phone connected to an EX4300 switch is assigned to voice VLAN 50 via LLDP-MED. However, when a PC is plugged into the IP phone's pass-through port, the PC cannot obtain an IP address via DHCP. The switch port is configured with interface-mode access and a native VLAN for data. What is the most likely root cause?

Choose an answer to begin — your selection is scored in the full session.

Accepted Answer

The native VLAN is not allowed or configured correctly on the access port, causing untagged PC traffic to be dropped.. If the switch port is in strict access mode without proper native VLAN forwarding or if untagged traffic is dropped, the PC fails. Alternatively, voice VLAN tagging mismatches can block native traffic.

Answer

The IP phone is stripping VLAN tags from the PC's DHCP requests.

Answer

The switch's DHCP snooping binding database has reached its maximum limit.

Answer

LLDP-MED is overriding the PC's MAC address and blacklisting it.

Question 2

You are reviewing syslog messages on an EX Series switch and see frequent entries indicating PoE power budgeting warnings. You want to configure a custom trap/syslog threshold so that warnings trigger when the total power consumption exceeds 85% of the total available PoE budget. How is this configured?

Accepted Answer

set poe budget-threshold 85. PoE threshold settings allow operators to set a percentage limit that triggers traps when power consumption nears capacity.

Answer

set system syslog host 192.168.1.10 poe-threshold 85

Answer

set poe threshold 85

Answer

set poe management-budget-threshold 85

Question 3

An administrator is configuring LLDP-MED on an EX Series switch for a new deployment of IP phones. Which TWO configuration steps are required to properly advertise network policies to these endpoints? (Choose two.)

Accepted Answer

Configure an LLDP-MED device policy for voice specifying the VLAN ID and priority.. Option A is correct because LLDP-MED network policy TLVs are what advertise voice VLAN information to IP phones, and on Junos EX switches this is done by configuring an LLDP-MED device policy (e.g., set protocols lldp-med interface all or a specific interface with a voice policy) that specifies the VLAN ID and 802.1p priority so the phone can tag its voice traffic correctly. Option C is correct because LLDP itself must be enabled globally under the protocols hierarchy (set protocols lldp interface all) before any LLDP-MED TLVs, including network policies, can be transmitted to the endpoints. Option B is not required for LLDP-MED policy advertisement; RSTP edge/fast-convergence is a separate Layer 2 convergence setting and does not carry VLAN or priority information to phones. Option D is unnecessary because CDP compatibility mode is only needed to interwork with Cisco Discovery Protocol devices, not for standards-based LLDP-MED advertisement. Option E is irrelevant since static ARP entries have nothing to do with LLDP-MED network policy delivery.

Answer

Enable spanning tree fast-convergence on all voice VLAN ports.

Answer

Enable CDP compatibility mode globally.

Answer

Configure a static ARP entry for every IP phone MAC address.

Question 4

An administrator wants to verify LLDP and LLDP-MED operation on an EX Series switch. Which THREE operational commands provide relevant diagnostic information? (Choose three.)

Accepted Answer

show poe interface. Operational verification of LLDP utilizes show lldp neighbor, show lldp med neighbors, and show poe interface commands.

Answer

show spanning-tree interface

Answer

show chassis routing-engine

Question 5

Which THREE conditions must be met for an EX Series switch to successfully supply PoE power to an attached IP phone? (Choose three.)

Accepted Answer

PoE must not be disabled on the specific switch interface.. PoE delivery requires physical power availability, correct hardware classification/detection, and administrative enablement on the port.

Answer

The switch port must be configured as a BGP peer.

Answer

The IP phone must be running Junos OS.

Question 6

An administrator notices that LLDP neighbors are failing to populate on an EX Series switch interface. Which THREE troubleshooting steps should be performed? (Choose three.)

Accepted Answer

Verify that LLDP is enabled globally under the protocols hierarchy.. Troubleshooting LLDP neighbor discovery involves checking global and interface LLDP status, physical link status, and packet captures/counters.

Answer

Verify that RSTP bridge priority is set to root.

Answer

Check BGP peer state for the LLDP neighbor.

Question 7

An EX4300 switch running Junos OS supports multiple PoE power management options. Which THREE PoE management modes or settings are valid in Junos configuration? (Choose three.)

Accepted Answer

Setting port priority (e.g., high, medium, low) for power shedding during overload.. Option B is correct because Junos PoE supports per-interface priority levels (high, medium, low, and sometimes critical) under the [edit poe interface] hierarchy, which determine the order in which ports shed power when the switch's PoE power budget is exceeded. Option D is correct because Junos PoE can allocate power using class-based methods (based on the IEEE 802.3af/at class detected during LLDP or CDP negotiation) or by actual measured consumption via the 'power-limit' and related settings, allowing efficient use of the available power budget. Option E is correct because Junos allows a manual maximum power limit per interface, configured with the 'maximum-power' statement in milliwatts (e.g., set poe interface ge-0/0/1 maximum-power 15000), which caps the power delivered to a powered device. Option A is not valid because OSPF is a Layer 3 routing protocol and has no role in PoE power management. Option C is not valid because Junos PoE does not provide inline power encryption keys; PoE delivers DC power and does not encrypt the powered link.

Answer

Setting automatic PoE routing metrics via OSPF.

Answer

Configuring inline power encryption keys for VoIP security.

Question 8

You are deploying a new IP telephony network on an EX4300 switch. The voice VLAN must be automatically communicated to connected IP phones using LLDP-MED. Which configuration parameter under system services lldp med fast-start-repeat-count must you configure to ensure rapid initial device discovery?

Accepted Answer

set protocols lldp-med fast-start-repeat-count 4. In Junos, LLDP-MED fast-start features help newly connected devices discover network policies faster. Configuring lldp med fast-start-repeat-count defines how many times fast-start packets are sent upon connection.

Answer

set system services lldp fast-start-count 4

Answer

set interfaces all lldp-med fast-start 4

Answer

set protocols lldp fast-start-repeat 4

Question 9

Which THREE statements are true regarding voice VLAN technologies and implementation on Junos EX Series switches? (Choose three.)

Accepted Answer

EX switches can advertise voice VLAN information to IP phones using LLDP-MED network policies.. Option A is correct because EX Series switches use LLDP-MED (Link Layer Discovery Protocol - Media Endpoint Discovery) network policies to advertise voice VLAN information, such as VLAN ID and 802.1p CoS priority, to IP phones so they can automatically tag voice traffic. Option B is correct because a single access port can be configured with a native (untagged) data VLAN for an attached PC and a voice VLAN (tagged) for the IP phone, typically using the 'set ethernet-switching-options voip' or 'voice-vlan' configuration on the interface. Option C is correct because a voice VLAN creates a separate Layer 2 broadcast domain, isolating voice traffic from user data traffic, which improves security and QoS. Option D is incorrect because voice VLANs are commonly configured on access ports facing IP phones, not restricted to routed core switch ports. Option E is incorrect because voice VLANs do not require transparent mode or disabling MAC learning; EX switches operate normally with MAC learning enabled while supporting voice VLANs.

Answer

Voice VLANs are restricted exclusively to routed core switch ports.

Answer

Voice VLANs require the switch to operate in transparent mode without MAC learning.

Question 10

An EX4300 switch is experiencing a PoE budget shortage, causing newly connected IP phones to be denied power. You need to change the PoE power management mode from the default to dynamic consumption-based allocation rather than static class-based allocation. Which command achieves this?

Accepted Answer

set poe management-mode dynamic. On Juniper EX switches, the PoE power management mode is configured with the `set poe management-mode` command. The default mode is `class`, which statically allocates the maximum power for the detected class (e.g., 15.4W for Class 3). Changing to `dynamic` enables consumption-based allocation, where the switch allocates only the actual power drawn by the powered device, allowing more devices to be powered within the same budget. Therefore, option B is correct.

Answer

set power-options allocation-mode consumed

Answer

set poe interface all priority medium

Answer

set system poe mode consumption

Question 11

You are troubleshooting an IP phone that is failing to learn its assigned voice VLAN via LLDP-MED from an EX4600 switch. You run show lldp interface ge-0/0/5 and verify LLDP is active. However, the phone's voice VLAN ID TLV is missing from the neighbor information. Which configuration command under the interface must be verified to ensure voice VLAN advertisements are properly transmitted?

Accepted Answer

set protocols lldp-med interface ge-0/0/5 network-policy voice. Voice VLAN configurations on access ports must be properly mapped using layer 2 options or voice-vlan specific commands so that LLDP-MED can populate the network policy TLV.

Answer

set switch-options voice-vlan-advertising enable

Answer

set protocols lldp interface ge-0/0/5 vlan-name voice

Answer

set protocols lldp interface ge-0/0/5 transport-address

Question 12

You need to configure an LLDP-MED network policy for voice traffic on an EX switch, ensuring that the DSCP value is set to 46 and the VLAN ID is set to 150. Which configuration achieves this?

Accepted Answer

set protocols lldp-med network-policy voice vlan 150 dscp 46. LLDP-MED network policies are defined under protocols lldp-med network-policy voice and reference application type voice, VLAN ID, and DSCP settings.

Answer

set system services lldp-med policy voice id 150 dscp 46

Answer

set protocols lldp network-policy voice-vlan 150 priority 46

Answer

set interfaces all lldp-med voice-vlan 150 dscp 46

Question 13

Which TWO actions occur by default on a Junos EX Series switch port when an IP phone successfully negotiates its voice VLAN using LLDP-MED? (Choose two)

Accepted Answer

The switch automatically configures the interface to forward traffic for the learned voice VLAN ID.. Option A is correct because when an EX Series switch receives the voice VLAN ID via LLDP-MED (using the Network Policy TLV), it automatically adds that VLAN to the interface's configuration and forwards tagged voice traffic for the learned VLAN ID, without requiring manual VLAN provisioning. Option C is correct because the LLDP-MED Network Policy TLV also carries Layer 2 priority (802.1p CoS) and DSCP values, which the switch applies to the voice traffic flow so that QoS marking is honored end-to-end. Option B is incorrect because the port does not become a full trunk with native VLANs removed; it operates in a voice-VLAN mode where untagged data traffic remains on the access VLAN and only voice traffic is tagged. Option D is incorrect because STP is not disabled on the interface by LLDP-MED negotiation; STP continues to run normally. Option E is incorrect because PoE is not shut down based on tagged data frames; LLDP-MED power negotiation does not trigger such an action.

Answer

The switch converts the access port into a full trunk port removing all native VLAN configurations.

Answer

The switch disables Spanning Tree Protocol on the interface to optimize voice convergence time.

Answer

The switch shuts down PoE on the port if the phone attempts to use tagged data frames.

Question 14

You are deploying IP phones on an EX4300 switch. The phones must receive VLAN and QoS information from LLDP-MED. You have configured the voice VLAN and enabled LLDP on all interfaces. However, the phones are not receiving the network policy. Which configuration step is required?

Accepted Answer

Enable LLDP-MED on the interface with the command set protocols lldp-med interface ge-0/0/1.0. LLDP-MED must be explicitly enabled on the interface to send network policy TLVs. Enabling LLDP globally is not sufficient. The correct command enables LLDP-MED on the specific interface, allowing the phone to receive VLAN and QoS parameters. Other options are either redundant, incorrect, or address different features.

Answer

Configure the voice VLAN under the [edit ethernet-switching-options] hierarchy

Answer

Enable LLDP on the interface with the command set protocols lldp interface ge-0/0/1.0

Answer

Configure the phone as a trusted device using the command set ethernet-switching-options secure-access-port interface ge-0/0/1.0

Question 15

You are deploying IP phones on an EX4300 switch. The phones must receive their voice VLAN assignment via LLDP-MED. You configure the interface with 'lldp-med' and create a network policy, but the phones do not receive the voice VLAN information. Which configuration step is missing?

Accepted Answer

Apply the network policy to the interface using the 'lldp-med interface network-policy ' command.. LLDP-MED network policies are configured separately and then applied to interfaces. The switch must be explicitly told which policy to advertise on which interface. Without the 'network-policy' binding under the interface, the switch will not include the network policy TLV in its LLDP-MED advertisements, so the phone cannot determine the voice VLAN.

Answer

Enable LLDP on the interface using the 'lldp interface <interface>' command.

Answer

Configure the interface as a trunk port using 'set interfaces <interface> unit 0 family ethernet-switching port-mode trunk'.

Answer

Set the voice VLAN ID under the 'protocols lldp-med' hierarchy using 'set protocols lldp-med voice-vlan <vlan-id>'.