JNCIP-ENT IP Telephony Features Practice Test 3 — 15 Questions

Question 1

You are troubleshooting an EX Series switch where an IP phone is not receiving PoE power. The switch port is configured for PoE, and the phone is known to work. Which two conditions could prevent the switch from supplying power to the phone? (Choose two.)

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

Accepted Answer

The interface is configured with 'poe disable'.. PoE power delivery can be blocked by either exhausting the switch's power budget or administratively disabling PoE on the port. These are two distinct and common causes. Other factors like cable type or LLDP-MED do not affect the switch's ability to provide power.

Answer

The phone is connected using a straight-through cable instead of a crossover cable.

Answer

The phone is not sending LLDP-MED packets to request power.

Answer

The switch is configured for PoE management mode 'class' and the phone's class exceeds the configured maximum power.

Question 2

You are configuring a voice VLAN on an EX2300 switch. The IP phone sends untagged traffic for voice and tagged traffic for data. You want to ensure that untagged frames are placed into the voice VLAN and tagged frames into the data VLAN. Which configuration accomplishes this?

Accepted Answer

Set the interface to access mode with voice VLAN as the access VLAN and enable VoIP. When a phone sends untagged voice and tagged data, the switch port should be configured with the voice VLAN as the native or access VLAN for untagged frames. Enabling VoIP on the interface ensures that tagged data frames are handled correctly, often by assigning them to a data VLAN. This configuration places untagged traffic into the voice VLAN and tagged traffic into the data VLAN.

Answer

Set the interface to access mode with voice VLAN enabled and data VLAN as the access VLAN

Answer

Set the interface to trunk mode with native VLAN voice and allow data VLAN tagged

Answer

Set the interface to trunk mode with native VLAN data and allow voice VLAN tagged

Question 3

You are deploying IP phones on an EX4300 switch. Phones must receive VLAN and QoS parameters before they can pass traffic. You have configured LLDP-MED on the access ports, but the phones are not receiving the advertised network policy. You verify that the interface is up and the phone is detected as an LLDP-MED endpoint. What should you do next to ensure the network policy is delivered?

Accepted Answer

Enable LLDP-MED network policy on the interface with the correct application type and VLAN ID.. LLDP-MED network policy must be explicitly configured on the interface to advertise voice VLAN and QoS parameters. Even with LLDP-MED enabled globally, the switch will not send the policy TLV unless it is defined for the interface. This allows the phone to automatically discover and configure its voice VLAN and priority, which is essential for proper IP telephony operation.

Answer

Set the PoE management mode to class on the interface.

Answer

Configure the interface as a trunk port carrying both data and voice VLANs.

Answer

Configure the voice VLAN as a tagged VLAN on the access port.

Question 4

You administer an EX4300 access switch running Junos OS that supports IP phones. The phones must receive voice VLAN and QoS policy information from the switch through LLDP-MED, but a recent security audit requires that LLDP be disabled on all uplink ports toward the distribution layer while remaining active on access ports. Which configuration accomplishes this requirement?

Accepted Answer

Leave LLDP enabled globally and remove LLDP from the uplink interfaces by deleting the interface stanza for those ports from the LLDP configuration.. LLDP on Junos EX Series is enabled by specifying interfaces under 'protocols lldp interface'. To keep LLDP-MED active for phones on access ports while suppressing LLDP toward the distribution layer, simply omit the uplink interfaces from the LLDP interface list. This preserves LLDP-MED TLV exchange on access ports and satisfies the security requirement without affecting the voice VLAN or QoS policy delivery to the phones.

Answer

Set 'protocols lldp-med interface ge-0/0/x' on access ports and 'protocols lldp interface all' with an 'except' statement for uplinks.

Answer

Apply a firewall filter on the uplink interfaces that discards Ethernet frames with EtherType 0x88CC, which is the LLDP EtherType.

Answer

Disable LLDP globally with 'set protocols lldp disable', then enable it under each access interface with 'set protocols lldp interface ge-0/0/x'.

Question 5

You are configuring an EX2300 switch to support an IP phone that requires a voice VLAN. The phone will send untagged traffic for voice and tagged traffic for data. Which configuration correctly assigns untagged frames to the voice VLAN and tagged frames to the data VLAN on interface ge-0/0/1?

Accepted Answer

set interfaces ge-0/0/1 unit 0 family ethernet-switching interface-mode trunk vlan members [ data voice ] native-vlan-id voice. To handle both untagged voice and tagged data on the same port, configure the interface as a trunk, allow both VLANs, and set the native VLAN to the voice VLAN. Untagged frames are then assigned to the native VLAN (voice), and tagged frames are assigned to their respective VLANs (data).

Answer

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

Answer

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

Answer

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

Question 6

You are configuring LLDP-MED on an EX Series switch to support IP phones. You want to ensure that the switch advertises its capabilities and network policies to the phones. Which command correctly enables LLDP-MED on interface ge-0/0/1?

Accepted Answer

set protocols lldp-med interface ge-0/0/1. The correct command to enable LLDP-MED on an interface is set protocols lldp-med interface ge-0/0/1. This enables the switch to send LLDP-MED TLVs, which are essential for IP phones to receive network policies. Other options contain syntax errors or target the wrong hierarchy, and thus would not work.

Answer

set protocols lldp-med interface ge-0/0/1.0

Answer

set protocols lldp-med enable interface ge-0/0/1

Answer

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

Question 7

You need to verify that an EX2300 switch is correctly sending LLDP-MED network policy information to an attached IP phone so the phone places its voice traffic in the correct VLAN. Which operational command shows the LLDP-MED neighbor details, including the advertised network policy, for the interface where the phone is connected?

Accepted Answer

show lldp neighbors detail interface ge-0/0/1. The 'show lldp neighbors detail' command on Junos EX Series includes LLDP-MED extensions, exposing the neighbor's MED device type, capabilities, and the network policy TLVs that carry voice VLAN and QoS information. Scoping the command to the specific interface where the IP phone is connected validates that the switch is advertising the expected policy to that phone.

Answer

show lldp neighbors interface ge-0/0/1

Answer

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

Answer

show ethernet-switching interfaces ge-0/0/1

Question 8

An administrator is configuring an EX Series switch for IP telephony. The switch must support both data and voice VLANs on a single access port. The IP phones are LLDP-MED capable and should automatically place voice traffic in VLAN 100, while data traffic remains untagged in VLAN 10. The administrator has already configured VLANs 10 and 100 and set the interface to access mode with VLAN 10. What additional configuration is required on the interface?

Accepted Answer

Configure 'lldp-med network-policy voice' with VLAN 100 on the interface.. To automatically assign the voice VLAN to an LLDP-MED capable phone, you must configure an LLDP-MED network policy for voice with the correct VLAN ID on the interface. This allows the phone to tag voice traffic with VLAN 100 while data traffic remains untagged in VLAN 10. The interface stays in access mode with VLAN 10, and the switch recognizes tagged voice frames from the phone.

Answer

Set the interface to trunk mode and add VLAN 100 to the allowed VLANs.

Answer

Enable LLDP on the interface and set the voice VLAN as the access VLAN.

Answer

Configure the interface as a voice VLAN port with VLAN 100 as the native VLAN.

Question 9

An EX Series switch is deployed in an office where IP phones and PCs share the same access ports. The phones must use a dedicated voice VLAN, and the attached PCs must use a separate data VLAN. LLDP-MED is used to tell the phones which VLAN to use. Which configuration on the access port accomplishes this requirement?

Accepted Answer

Configure the port as an access port in the data VLAN and enable LLDP-MED with a network policy that specifies the voice VLAN as tagged.. To support a phone and PC on one access port with separate VLANs, the port is configured as an untagged member of the data VLAN for the PC, and LLDP-MED network policy tells the phone to tag its voice traffic with the voice VLAN ID. The phone then sends tagged voice frames and passes untagged PC frames through, providing clean separation without manual phone configuration.

Answer

Configure the port with 'voice-vlan' and 'data-vlan' statements under the interface, and enable LLDP on the port.

Answer

Configure the port as an access port in the voice VLAN and use LLDP-MED to assign the data VLAN to the PC.

Answer

Configure the port as a trunk port carrying both the data and voice VLANs, and rely on the PC to tag its traffic with the data VLAN.

Question 10

You are deploying IP phones that rely on LLDP-MED to receive voice VLAN and QoS parameters from an EX Series switch. Security policy requires that LLDP be disabled on uplink ports but remain active on access ports. Which TWO configuration elements are required to meet these requirements? (Choose two.)

Accepted Answer

List only the access interfaces under 'protocols lldp interface' so LLDP is active solely on those ports.. Meeting the requirement involves two elements: scoping LLDP to the access interfaces by listing only those ports under 'protocols lldp interface', which keeps LLDP and LLDP-MED active for the phones while excluding uplinks, and defining an LLDP-MED network policy that carries the voice VLAN ID, Layer 2 priority, and DSCP value. Together, these ensure phones receive the correct voice configuration while uplinks remain free of LLDP traffic.

Answer

Apply a firewall filter on the uplink interfaces that discards LLDP frames based on EtherType 0x88CC.

Answer

Enable LLDP globally with 'set protocols lldp' and then disable it on uplinks using 'set protocols lldp interface ge-0/0/x disable'.

Answer

Configure the uplink ports as trunk ports and the access ports as access ports in the voice VLAN only.

Question 11

You are troubleshooting an IP phone that is failing to discover its voice VLAN via LLDP-MED on an EX4600 switch. You issue the show lldp interface command and see that LLDP is transmitting properly, but the phone reports no voice VLAN TLV received. What is the most likely cause of this issue?

Accepted Answer

The LLDP-MED network policy for voice has not been defined and mapped to the interface or device profile.. LLDP-MED network policy must be explicitly configured and tied to the interface or globally mapped so that the switch populates the voice VLAN TLV in its outbound LLDP-MED packets.

Answer

The voice VLAN is not configured under the switch-options vlan-group hierarchy.

Answer

IEEE 802.1p priority marking is missing from the global bridge-options statement.

Answer

LLDP advertisement interval is set too high, causing timeout on the phone.

Question 12

An administrator implements LLDP-MED on an EX Series switch network. To prevent unauthorized devices from masquerading as IP phones and requesting voice VLAN access, which feature should be combined with LLDP-MED?

Accepted Answer

IEEE 802.1X port-based authentication with dynamic VLAN assignment. MAC Radius or 802.1X authentication combined with VLAN assignment and LLDP-MED ensures security before voice policies are trusted.

Answer

Storm control with broadcast filtering

Answer

DHCP snooping and Dynamic ARP Inspection (DAI)

Answer

IP Source Guard

Question 13

You notice that an EX4300 switch power budget calculation is set to use 'class-based' allocation. What does this mean regarding how power is reserved for connected IP phones?

Accepted Answer

The switch reserves power according to the maximum wattage defined by the device's hardware PoE class (e.g., Class 0, Class 3).. Class-based power allocation reserves the maximum wattage specified by the device's 802.3af/at power class, regardless of actual consumption.

Answer

The switch allocates a flat 15.4W to every port regardless of what device is plugged in.

Answer

The switch shares a dynamic pool where ports draw power on a first-come, first-served basis without limits.

Answer

The switch allocates power based on real-time LLDP-MED reported consumption values.

Question 14

An IP phone connected to an EX4600 switch fails to power up. You run show poe interface ge-0/0/1 and find the status displays 'Hardware error'. What is the most appropriate troubleshooting step?

Accepted Answer

Check the switch's power supply units (PSUs) and internal PoE controller status using show chassis power.. The 'Hardware error' status in 'show poe interface' indicates a physical or internal hardware fault with the PoE controller or power supply, not a configuration issue. Checking the switch's PSUs and PoE controller status with 'show chassis power' is the appropriate first step to diagnose power delivery problems. This command displays power supply status, capacity, and any failures.

Answer

Reconfigure the port from access mode to trunk mode.

Answer

Modify the LLDP-MED network policy timeout value to allow longer initialization.

Answer

Disable spanning tree protocol on the interface.

Question 15

What does the LLDP-MED acronym stand for in the context of enterprise networking and IP telephony?

Accepted Answer

Link Layer Discovery Protocol - Media Endpoint Discovery. LLDP-MED stands for Link Layer Discovery Protocol - Media Endpoint Discovery.

Answer

Link Layer Device Protocol - Managed Ethernet Deployment

Answer

Local Loop Discovery Protocol - Mobile Ethernet Device

Answer

Logical Link Discovery Protocol - Multi-access Equipment Design