JNCIP-ENT IP Telephony Features — 25 Questions

Question 1

An administrator notices that an EX4300 switch is supplying power using LLDP-MED power negotiation, but the IP phone is drawing more power than the initial hardware class allows. Where would you check the advertised LLDP-MED TLV power value received from the phone?

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

Accepted Answer

show lldp neighbor interface ge-0/0/10 detail. The show lldp neighbor interface command displays detailed TLVs received from connected LLDP-MED endpoints, including power requirements.

Answer

show system lldp-med power-statistics

Answer

show poe interface ge-0/0/10 lldp-negotiation

Answer

show ethernet-switching interfaces lldp ge-0/0/10

Question 2

Which command allows you to verify the real-time PoE power consumption, allocated wattage, and operational status of all interfaces on an EX Series switch?

Accepted Answer

show poe interface. The show poe interface operational command displays detailed power metrics per port.

Answer

show interfaces diagnostics poe

Answer

show chassis poe status

Answer

show lldp poe-status

Question 3

You are configuring a voice VLAN on an EX Series switch access port where an IP phone is connected in series with a PC. Which configuration is required on the switch interface to handle both tagged voice traffic and untagged data traffic?

Accepted Answer

Configure the interface as access mode with both voice-vlan and native-vlan parameters.. On an EX Series switch, an access port configured with both 'voice-vlan' and 'native-vlan' parameters can handle tagged voice traffic (on the voice VLAN) and untagged data traffic (on the native/access VLAN). The 'voice-vlan' statement enables the port to recognize and tag voice frames, while the native VLAN handles untagged data frames from the daisy-chained PC. This is the required configuration for IP phone + PC on a single access port.

Answer

Configure the port as an RSTP edge port with voice optimization.

Answer

Configure the port as a pure trunk port blocking all native VLAN traffic.

Answer

Configure the port using bridge-domains with dual-tagging (QinQ).

Question 4

An EX3400 switch experiences a total PoE power budget exhaustion after multiple high-power IP phones and security cameras are plugged in. You want to ensure that if a power deficit occurs, the switch immediately cuts power to lower-priority ports while maintaining power to executive phones on specific ports. How should you configure this?

Accepted Answer

set poe interface all priority low and set poe interface ge-0/0/1 to ge-0/0/4 priority high. Priority-based PoE allocation allows administrators to assign priorities (high, low, medium) to specific interfaces to dictate shedding order.

Answer

set poe power-budget-threshold 80

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set poe management-mode class-based

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set interfaces all poe shutdown-on-overload

Question 5

What is the default behavior of an EX Series switch when an LLDP-MED capable IP phone connects and requests a network policy for voice VLAN?

Accepted Answer

The switch responds with the configured LLDP-MED network policy containing the voice VLAN ID and Layer 2/3 priority markings.. LLDP-MED automatically provisions network policies to capable endpoints when properly configured on the switch.

Answer

The switch drops the LLDP packet unless explicit authorization is configured.

Answer

The switch converts the port into a full trunk interface automatically.

Answer

The switch reboots the port to force DHCP discovery.

Question 6

An administrator needs to enable LLDP globally on an EX Series switch running Junos OS to support IP phones. Which command accomplishes this task?

Accepted Answer

set lldp global-enable. LLDP is enabled globally under the protocols hierarchy in Junos OS.

Answer

set system lldp enable

Answer

set ethernet-switching-options lldp

Question 7

You are configuring Power over Ethernet (PoE) on an EX4300 switch to power an IP phone requiring 15.4W (802.3af). By default, the switch allocates power based on dynamic classification. However, the IP phone frequently reboots under heavy traffic load. Which command should you configure on the switch interface to ensure the phone receives a guaranteed dedicated power budget?

Accepted Answer

set poe interface ge-0/0/14 consumption 15400. The command 'set poe interface ge-0/0/14 consumption 15400' configures a static power consumption value for the interface, ensuring that the switch allocates a guaranteed 15.4W to the phone regardless of dynamic classification. This prevents the phone from rebooting due to insufficient power under heavy load.

Answer

set protocols lldp-med interface ge-0/0/14 power-over-ethernet budget 15400

Answer

set interfaces ge-0/0/14 poe priority high

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set poe interface ge-0/0/14 max-power 15.4w

Question 8

Which command displays the global status, TLV counters, and operational state of LLDP on an EX Series switch?

Accepted Answer

show lldp. show lldp provides system-wide operational data for LLDP.

Answer

show protocols lldp summary

Answer

show system lldp status

Answer

show ethernet-switching lldp

Question 9

You are configuring voice VLANs on an EX2300 switch. You want to ensure that untagged frames entering the interface are placed into the data VLAN, while frames generated by the attached IP phone are tagged with VLAN 50. Which CLI configuration snippet correctly achieves this?

Accepted Answer

set interfaces ge-0/0/1 unit 0 family ethernet-switching interface-mode access vlan members data-vlan and set interfaces ge-0/0/1 unit 0 family ethernet-switching voice-vlan 50. Configuring the interface with a native VLAN for data and a voice-vlan statement for the phone is standard Junos syntax.

Answer

set interfaces ge-0/0/1 unit 0 family ethernet-switching interface-mode access native-vlan data-vlan voice-vlan v50

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set protocols lldp-med interface ge-0/0/1 vlan 50

Answer

set interfaces ge-0/0/1 unit 0 family ethernet-switching vlan members [ data-vlan voice-vlan ]

Question 10

You want to configure LLDP-MED to advertise a specific voice VLAN (VLAN ID 200) with a DSCP value of 46 to all connected IP phones across all switch ports. Which configuration hierarchy is used to define this global network policy in Junos OS?

Accepted Answer

set protocols lldp-med device-policy voice vlan 200 dscp 46. LLDP-MED policies are configured under the protocols lldp-med hierarchy.

Answer

set poe lldp-policy voice 200

Answer

set ethernet-switching-options voice-vlan id 200

Answer

set system lldp-med voice-vlan 200

Question 11

Which command is used to view LLDP-MED specific neighbor details, including device type, capabilities, and network policies on an EX Series switch?

Accepted Answer

show lldp med neighbors detail. show lldp med neighbors detail displays comprehensive LLDP-MED TLV data for connected devices.

Answer

show protocols lldp-med status

Answer

show system lldp-med neighbors

Answer

show lldp neighbor interface detail

Question 12

An enterprise network uses IP phones that require LLDP-MED to receive voice VLAN information. However, security policy dictates that LLDP should be disabled on all user-facing access ports that do not have IP phones. Which configuration statement disables LLDP on a per-interface basis?

Accepted Answer

set protocols lldp interface ge-0/0/25 disable. On Junos EX switches, LLDP is disabled per interface under the [edit protocols lldp] hierarchy using the 'disable' statement. The correct syntax is 'set protocols lldp interface ge-0/0/25 disable', which stops LLDP transmit/receive on that specific port while leaving LLDP enabled globally for ports that need it (e.g., IP phone ports). This satisfies the security policy of disabling LLDP on non-phone access ports.

Answer

set interfaces ge-0/0/25 lldp-state off

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set ethernet-switching-options lldp interface ge-0/0/25 restrict

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set protocols lldp interface ge-0/0/25 action block

Question 13

You are troubleshooting voice quality issues on an IP phone connected to an EX Series switch. You suspect that the switch is not trusting the DSCP markings (DSCP 46) sent by the IP phone. Which Junos class-of-service (CoS) configuration ensures that incoming voice traffic DSCP bits are trusted at the ingress interface?

Accepted Answer

set class-of-service interfaces ge-0/0/5 classifier dscp default. Configuring forwarding-class and rewrite rules or trusting DSCP at ingress is handled via CoS classifiers.

Answer

set protocols lldp-med trust-qos

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set interfaces ge-0/0/5 family ethernet-switching trust-dscp

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set poe interface ge-0/0/5 qos-trust

Question 14

You are configuring an EX3400 switch to support IP phones that require power redundancy. Which PoE management feature allows the switch to allocate power based on available PSU capacity while reserving a safety margin?

Accepted Answer

The system automatically accounts for redundant power supplies, but power management thresholds can be adjusted via system PoE budget settings.. PoE power management configuration allows setting guard bands or managing power budgets based on active power supplies.

Answer

set chassis poe redundant-psu enable

Answer

set poe management-mode power-limit

Answer

set poe redundancy-mode full

Question 15

Which Junos command displays the LLDP neighbor information specifically for a single interface, such as ge-0/0/1?

Accepted Answer

show lldp neighbor interface ge-0/0/1. show lldp neighbor interface allows filtering LLDP neighbors by specific interface names.

Answer

show protocols lldp interface ge-0/0/1 neighbors

Answer

show interfaces lldp neighbor ge-0/0/1

Answer

show lldp interface ge-0/0/1 status

Question 16

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?

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 17

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 18

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 19

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 20

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.