JNCIP-ENT IP Telephony Features Practice Test 4 — 15 Questions

Question 1

An administrator configures PoE management mode on an EX4300 switch to 'consumption'. An IP phone connects, but before booting up completely, the switch denies power. Upon investigation, you find that the switch's static power reservation table is maxed out. What is the reason for this behavior in consumption mode?

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

Accepted Answer

Consumption mode still requires an initial allocation based on maximum class rating until LLDP-MED or CDP successfully negotiates the lower actual consumption value.. Even in consumption mode, Junos initially allocates power based on class or a default maximum until the device negotiates its actual consumption via LLDP-MED or CDP.

Answer

Consumption mode only works with non-PoE+ devices.

Answer

Consumption mode requires manual CLI power limits for every single port.

Answer

Consumption mode disables all dynamic power allocations permanently.

Question 2

Which LLDP TLV (Type-Length-Value) is mandatory for LLDP-MED operation and is used to distinguish media endpoint devices from standard network switches and routers?

Accepted Answer

LLDP-MED Capabilities TLV. The Capabilities TLV allows devices to advertise whether they are standard bridge/router devices or LLDP-MED endpoints.

Answer

MAC Address TLV

Answer

Port ID TLV

Answer

System Description TLV

Question 3

You are troubleshooting a power budget shortfall on an EX4300 switch where multiple PoE devices are failing to power up. Which TWO actions can you take to resolve or mitigate this power deficit? (Choose two.)

Accepted Answer

Configure critical IP phone ports with a high PoE priority so they are not shut down during a power deficit.. Option C is correct because on EX4300 PoE ports you can assign a PoE priority (for example, high) so that during a power budget deficit the switch sheds lower-priority ports first and preserves power for critical IP phones. Option D is correct because you can manually control per-port power allocation using the 'power-limit' configuration with either class/consumption mode or an explicit wattage value, reducing the total allocated power and bringing the budget back within the switch's capacity. Options A, B, and E do not address PoE power budgeting: disabling LLDP-MED would not reduce power draw and could actually disrupt phone power negotiation, RSTP root guard is a Layer 2 loop-prevention feature unrelated to PoE, and converting access ports to trunks has no effect on power consumption or allocation.

Answer

Disable LLDP-MED globally to force all phones to draw maximum class power.

Answer

Enable RSTP root guard on all voice interfaces.

Answer

Convert all access ports to trunk ports.

Question 4

When deploying IP phones that utilize a voice VLAN on EX Series access ports, which THREE characteristics or configurations typically apply to this design? (Choose three.)

Accepted Answer

Untagged traffic generated by an attached PC passes through the phone into the native VLAN of the switch port.. Option B is correct because in a typical voice VLAN deployment the PC's untagged frames are forwarded by the phone and land in the switch port's native (data) VLAN, keeping PC traffic separate from voice traffic. Option C is correct because the access port carries both a native data VLAN for the attached PC and a tagged voice VLAN for the phone, which is the standard EX Series access-port voice VLAN design. Option D is correct because the IP phone itself applies the 802.1Q tag with the configured voice VLAN ID to its own voice frames, which is how the switch distinguishes voice from data. Option A is wrong because a pure Layer 3 routed interface does not carry 802.1Q-tagged voice VLAN traffic in this access-port design. Option E is wrong because BGP is a routing protocol between Layer 3 devices and has no role in phone-to-switch voice VLAN tagging or access-port operation.

Answer

The switch port must be configured as a pure Layer 3 routed interface.

Answer

The IP phone must be configured to run BGP to exchange voice routes with the switch.

Question 5

Which THREE parameters are typically included in an LLDP-MED network policy TLV for voice application? (Choose three.)

Accepted Answer

VLAN ID. The LLDP-MED Network Policy TLV for a voice application carries the parameters a VoIP endpoint needs to tag its traffic correctly: option A (VLAN ID) tells the phone which voice VLAN to use, option D (DSCP Value for Layer 3 QoS) provides the Layer 3 marking the phone should apply to voice RTP/signaling, and option E (Layer 2 Priority, 802.1p) supplies the CoS value for the 802.1Q tag. These three fields—VLAN ID, Layer 2 priority, and DSCP—are the standard contents of the Network Policy TLV defined in ANSI/TIA-1057 for LLDP-MED, along with an application type and unknown-policy flag. Option B (IP Phone MAC Address) is not part of the policy TLV; the phone's MAC is learned via normal source-MAC learning or the LLDP chassis ID, not advertised as a policy parameter. Option C (Switch Power Supply Serial Number) is unrelated to QoS/VLAN policy and would only appear in inventory or power-management contexts, not in a network policy TLV.

Answer

IP Phone MAC Address

Answer

Switch Power Supply Serial Number

Question 6

Which THREE statements describe the behavior of LLDP-MED capability on Junos EX Series switches? (Choose three.)

Accepted Answer

It automates network policy configuration for voice, video, and guest VLANs.. LLDP-MED enables advanced capabilities like device location, inventory management, and network policies for endpoints.

Answer

It replaces the need for Ethernet switching entirely by converting access ports into routed links.

Answer

It requires OSPFv3 to be running on all connected IP phones.

Question 7

When configuring voice VLANs and PoE on an EX Series switch, which THREE benefits are achieved by implementing LLDP-MED alongside standard PoE? (Choose three.)

Accepted Answer

Dynamic power negotiation allowing devices to request exact wattage rather than class maximums.. LLDP-MED extends standard LLDP with media endpoint discovery TLVs, so option A is correct because its Extended Power-via-MDI TLV lets an endpoint negotiate its actual power requirement in watts instead of being limited to the 802.3af/at class maximum, improving PoE budget efficiency. Option C is correct because LLDP-MED inventory TLVs (such as hardware revision, firmware revision, software revision, serial number, manufacturer name, and asset ID) are exchanged with the switch, enabling asset management and inventory tracking of attached endpoints. Option E is correct because the LLDP-MED Network Policy TLV carries the voice VLAN ID and Layer 2 priority, allowing an IP phone to discover and automatically tag its voice traffic with the correct VLAN without manual static provisioning. Option B is wrong because LLDP-MED does not eliminate Layer 2 broadcast traffic; broadcasts such as ARP and DHCP are still flooded within their broadcast domains. Option D is wrong because LLDP-MED does not configure IPsec VPN tunnels; IPsec is a security protocol configured independently and is not part of LLDP-MED signaling.

Answer

Elimination of all Layer 2 broadcast traffic on the switch.

Answer

Automatic configuration of IPsec VPN tunnels on the switch.

Question 8

You are configuring an EX Series switch to support IP phones that require both data and voice VLAN segregation on a single access port. You implement an access port configured with a voice VLAN. Which underlying Junos mechanism allows the switch to process untagged data traffic into the native/access VLAN and tagged voice traffic into the voice VLAN simultaneously?

Accepted Answer

Configuring an access port with the voice-vlan statement, which automatically handles tagging for the specified voice VLAN ID while keeping data untagged.. On Junos EX switches, configuring an access port with the 'voice-vlan' statement automatically enables the port to accept untagged data traffic into the native/access VLAN and tagged voice traffic into the specified voice VLAN. The switch internally treats the port as a special access port that can process both tagged and untagged frames, without requiring a full trunk configuration. This is the standard Junos mechanism for IP phone + PC daisy-chain deployments.

Answer

Configuring a trunk port with native-vlan-id and voice-vlan parameters.

Answer

Implementing IEEE 802.1ad provider bridging to double-tag voice and data frames.

Answer

Enabling port-based authentication with dynamic VLAN assignment via RADIUS.

Question 9

An administrator needs to configure PoE power management on an EX3400 switch to prioritize port ge-0/0/0 for a critical emergency IP phone. Which statement correctly describes the default PoE priority behavior on Junos EX switches if no explicit priority is configured?

Accepted Answer

All ports default to low priority, and power allocation is determined by port index order when budgets are constrained.. By default, all PoE ports on Junos EX switches are set to low priority. When the power budget is constrained, power allocation is determined by port index order (e.g., ge-0/0/0 before ge-0/0/1). This means that lower-numbered ports are given precedence. To prioritize a critical port, you must explicitly configure a higher priority.

Answer

All ports default to high priority and allocate power on a first-come, first-served basis.

Answer

PoE is disabled by default until an explicit priority is assigned to the interface.

Answer

Critical ports must be placed in a dedicated PoE policer to prevent disconnection.

Question 10

A network administrator needs to verify the PoE status, power draw, and allocated class for all connected IP phones across all interfaces on an EX2300 switch. Which operational command should be used?

Accepted Answer

show poe interface. The command show poe interface provides detailed information about PoE status, power consumption, class, and priority on EX switches.

Answer

show ethernet-switching poe status

Answer

show lldp med interface

Answer

show chassis power detail

Question 11

When configuring Power over Ethernet (PoE) on an EX Series switch, which THREE parameters can be explicitly managed or configured per interface? (Choose three)

Accepted Answer

Port priority (low, high, critical). Option A is correct because EX Series switches let you set the PoE port priority to low, high, or critical, which determines the order in which powered devices are dropped when the switch's power budget is exceeded. Option B is correct because PoE can be administratively disabled per interface, for example with the 'set poe interface ge-0/0/1 disable' command, cutting power to that port. Option E is correct because you can explicitly configure the maximum power allocated to an interface in watts or milliwatts, such as 'set poe interface ge-0/0/1 maximum-power 15.4', to cap what a powered device may draw. Option C is not a configurable PoE parameter; voltage step-down behavior is not a user-managed threshold on EX switches. Option D is also not configurable, since cable resistance compensation is handled internally by the switch rather than exposed as a per-interface profiling setting.

Answer

Dynamic voltage step-down thresholds based on cable length

Answer

Automatic cable resistance compensation profiling

Question 12

Which THREE requirements must be met for an IP phone to successfully discover and use a voice VLAN configured via LLDP-MED on an EX Series switch? (Choose three)

Accepted Answer

An LLDP-MED network policy defining the voice VLAN must be configured and applied to the interface.. Option A is correct because LLDP-MED conveys VLAN assignment to the phone through a network policy TLV, so a network policy that defines the voice VLAN (and its VLAN ID/802.1p CoS) must be configured and applied to the interface for the phone to learn the voice VLAN. Option D is correct because LLDP-MED is an endpoint-discovery extension; the IP phone must support LLDP-MED and be able to process the network policy TLV to act on the advertised voice VLAN. Option E is correct because LLDP-MED depends on LLDP being enabled both globally and on the specific interface so the TLVs are transmitted to the attached phone. Option B is not required because LLDP-MED voice VLAN discovery is independent of 802.1X and RADIUS dynamic VLAN assignment. Option C is not required because the voice VLAN can be a Layer 2 VLAN and does not need Layer 3 routing or an IRB interface for LLDP-MED discovery.

Answer

802.1X authentication must be enabled with dynamic VLAN assignment configured on a RADIUS server.

Answer

The switch must be configured in Layer 3 routing mode with an IRB interface for the voice VLAN.

Question 13

You administer an EX4300 switch that connects to a third-party IP phone which relies on LLDP-MED to learn its voice VLAN and DSCP marking. The phone boots and registers, but call audio is marked best-effort and the phone places itself in the native data VLAN. You confirm the phone's LLDP-MED stack is enabled. On the switch interface you issued 'set protocols lldp-med interface ge-0/0/12.0' and committed, yet the phone still receives no network policy. Which configuration element must you add to deliver the voice parameters?

Accepted Answer

Define an LLDP-MED network policy under [edit protocols lldp-med] that specifies the voice application type, VLAN ID, and DSCP value, then apply it to the interface.. LLDP-MED advertises a network policy TLV only when an administrator explicitly defines one under the lldp-med hierarchy with an application type, VLAN identifier, and Layer 2/3 priority information. Merely enabling the protocol on the interface advertises device capabilities and inventory but no voice parameters. The policy is what instructs the phone which VLAN to join and how to mark its RTP traffic, resolving both the wrong-VLAN and best-effort marking symptoms.

Answer

Configure 'set ethernet-switching-options voip interface ge-0/0/12.0 vlan voice' so Junos generates the MED policy automatically for the phone.

Answer

Assign the interface to a trunk port with 'set interfaces ge-0/0/12 unit 0 family ethernet-switching port-mode trunk' and add the voice VLAN to the allowed list.

Answer

Enable LLDP globally with 'set protocols lldp interface all' so that the MED TLVs are carried inside standard LLDP frames toward the phone.

Question 14

An administrator is troubleshooting a Juniper EX Series switch where an IP phone connected to ge-0/0/10 is not receiving PoE power. The switch is an EX4300 with PoE+ capable ports. The administrator runs 'show poe interface ge-0/0/10' and sees 'Status: Disabled'. The interface is administratively up and LLDP is operational. What is the most likely cause?

Accepted Answer

PoE has been disabled on the interface with the 'disable' command under the PoE hierarchy.. The 'Disabled' status in the PoE interface output specifically indicates that PoE is administratively turned off for that port. This is typically done with the 'disable' command under the PoE interface configuration. Even if the port is up and LLDP is functioning, PoE will not be supplied until it is re-enabled. This is a common misconfiguration when PoE is disabled for power saving or security.

Answer

The connected device does not support IEEE 802.3af/at and is not drawing power.

Answer

LLDP-MED has not been configured on the interface, preventing PoE negotiation.

Answer

The PoE controller has reached its maximum power budget and has disabled the port.

Question 15

An EX4300 switch is configured with PoE management mode 'class' on all access ports. A new IP phone that advertises LLDP-MED power requirements is connected, but the phone powers on and then immediately reboots in a loop. The switch logs show the interface powering the port, then dropping power shortly after. Which action is most likely to resolve the phone boot loop?

Accepted Answer

Verify the switch's total PoE power budget and the sum of class-based reservations; if the budget is exhausted, reduce the number of powered ports or add a power supply.. Class-based PoE management reserves power according to the class advertised by the powered device. When the total of those reservations exceeds the switch's PoE budget, the switch may power a port, detect insufficient headroom, and drop power, producing a boot loop. Verifying the budget and the aggregate class reservations, then adding a power supply or reducing the number of powered ports, resolves the condition reliably.

Answer

Configure 'set poe interface ge-0/0/x maximum 30.0' to raise the per-port power limit above the class-based allocation.

Answer

Change the PoE management mode to 'consumption' so the switch allocates power based on actual usage rather than class.

Answer

Disable LLDP-MED power negotiation on the port so the switch falls back to IEEE 802.3af class-based detection, which matches the phone's actual class.