JNCIP-ENT Hard Questions — 25 Difficult Questions

Question 1

An engineer is troubleshooting multicast forwarding and RPF failures on a Junos routing instance. Which THREE conditions will cause a multicast RPF check failure? (Choose three)

Accepted Answer

The route to the source points towards a null or reject route.. RPF failures occur when the incoming interface for a multicast packet does not match the reverse path towards the source in the routing table, when no route exists, or when the routing table source differs.

Answer

IGMPv2 leave messages are received on an interface without active listeners.

Answer

PIM hello messages are exchanged with an incorrect hold time.

Question 2

You need to configure OSPFv2 graceful restart as a helper on a Junos router to assist neighboring routers during their routing engine switchover. Which command enables helper mode?

Accepted Answer

set protocols ospf graceful-restart helper. By default, OSPF graceful restart helper mode is enabled on Junos routers. To explicitly configure or modify it, you use the 'graceful-restart helper' command under protocols ospf.

Answer

set routing-options graceful-restart ospf helper

Answer

set protocols ospf graceful-restart router-role helper

Answer

set protocols ospf helper-mode enable

Question 3

Which THREE features or parameters can be configured under the 'protocols dot1x' interface hierarchy on an EX Series switch? (Choose two) -> wait, prompt says Which THREE, let's select three: supplicant timeout, max-retries, and guest-vlan.

Accepted Answer

max-retries. Under protocols dot1x interface hierarchy, you can configure timers like supp-timeout, retries/max-retries, guest-vlan, and fallback actions.

Answer

captive-portal-profile

Answer

radius-server-group

Question 4

Which THREE actions occur during the EVPN Designated Forwarder (DF) election process on a multi-homed Ethernet segment? (Choose three)

Accepted Answer

A Designated Forwarder is elected to forward BUM traffic from the core to the multi-homed site.. DF election uses Route Type 4 (Ethernet Segment routes) to exchange reachability, determines the forwarder based on preference and algorithms, and assigns responsibility for BUM traffic forwarding.

Answer

All participating PEs simultaneously forward BUM traffic to maximize bandwidth utilization.

Answer

MAC mobility sequence numbers are reset to zero during the election.

Question 5

An operator configures BGP attribute value manipulation using a Junos routing policy. Specifically, the policy uses 'as-path-action prepend' combined with community matching. When is this outbound policy evaluated relative to BGP route selection?

Accepted Answer

When advertising routes to a BGP peer, after the best path has been chosen.. Outbound export policies are evaluated when advertising routes to peers, after the best path has been selected locally.

Answer

During the initial import processing from EBGP peers before next-hop resolution.

Answer

Before the best path is selected, affecting the local routing table calculation.

Answer

During the route selection algorithm right after MED comparison.

Question 6

You are deploying IP phones on an EX4300 switch. The phones require PoE+ (802.3at) and must be allocated power based on their actual consumption rather than a fixed class. Which PoE management mode should you configure on the switch?

Accepted Answer

consumption. The 'consumption' mode allocates power based on actual power draw, which is more efficient than class-based or static allocation. This is particularly useful for PoE+ devices like IP phones that may not always draw maximum power, allowing the switch to support more devices within its power budget.

Answer

class

Answer

static

Answer

priority

Question 7

Which TWO actions can you take in Junos OS to optimize OSPF convergence times in a large enterprise network? (Choose two)

Accepted Answer

Configure faster Hello and Dead intervals on transit interfaces.. OSPF convergence can be accelerated by tuning SPF schedule delays (spf-options) and adjusting interface-specific hello and dead intervals.

Answer

Disable link-state acknowledgement pacing globally.

Answer

Convert all backbone areas into completely stubby areas.

Answer

Increase the SPF hold-down timer to allow network stabilization before running computations.

Question 8

An administrator is designing a high-availability PIM sparse-mode network. Which THREE mechanisms are used to provide redundancy for Rendezvous Points (RPs)? (Choose three)

Accepted Answer

Anycast RP with MSDP peering between multiple RPs. RP redundancy is typically achieved using static Anycast RP with MSDP, Bootstrap Router (BSR) dynamic discovery with multiple Candidate RPs, or Auto-RP (vendor-specific).

Answer

IGMP snooping querier election redundancy across core switches

Answer

Static RP configuration with multiple backup RP IP addresses configured on every router

Question 9

When designing a high-scale enterprise campus network using Juniper EX Series switches, which THREE best practices should be followed for Spanning Tree Protocol design? (Choose three)

Accepted Answer

Enable BPDU guard and loop guard on all edge access ports.. Best practices include placing root bridges at the core/distribution layer, using edge protection features, and maintaining consistent region parameters.

Answer

Use default bridge priority values on all core switches to allow automated root election.

Answer

Disable Spanning Tree entirely on all access ports to ensure faster convergence.

Question 10

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 11

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 12

You need to prevent an OSPF interface from participating in Designated Router (DR) election, forcing it to always act as a DROTHER, even if it has the highest priority. How is this achieved in Junos?

Accepted Answer

set protocols ospf area 0.0.0.0 interface xe-0/0/0.0 no-dr-election. Setting the OSPF interface priority to 0 prevents the router from participating in DR/BDR elections and forces it to become a DROTHER.

Answer

set protocols ospf area 0.0.0.0 interface xe-0/0/0.0 disable-dr

Answer

set protocols ospf area 0.0.0.0 interface xe-0/0/0.0 drother-only

Question 13

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

Answer

set poe management-mode class-based

Answer

set interfaces all poe shutdown-on-overload

Question 14

When applying a rewrite rule on an interface, you notice that packets are being remarked incorrectly. You realize that both a DSCP rewrite rule and an IEEE 802.1p rewrite rule are configured on the same physical interface. What is the rule regarding multiple rewrite rules on a single interface in Junos?

Accepted Answer

Different rewrite rule types (such as DSCP and ieee-802.1) can be applied simultaneously on the same logical interface. Junos allows only one rewrite rule per packet header type (e.g., one DSCP, one 802.1p) per logical interface, but you can have different header types applied simultaneously if they map to different packet layers.

Answer

Applying multiple rewrite rules causes an automatic system kernel crash

Answer

Only one rewrite rule total can be applied per logical interface regardless of type

Answer

Only Layer 2 rewrite rules are permitted on trunk ports

Question 15

An administrator needs to implement a traffic conditioning profile on a Juniper MX Series router to limit traffic to a specific burst size and drop packets exceeding the rate. Which policing action parameter is required to ensure that exceeding traffic is dropped immediately without coloring?

Accepted Answer

discard. A policer in Junos uses policer action statements like loss-priority or discard. To drop non-compliant traffic immediately, the action discard is configured.

Answer

forwarding-class

Answer

transmit

Answer

mark-action

Question 16

You are troubleshooting a scenario where multi-field classifiers and behavior aggregate classifiers are both configured on the same ingress interface. In what order does Junos process classification?

Accepted Answer

Behavior aggregate classification is evaluated first, and multi-field classification can override the result. Junos processes Behavior Aggregate (BA) classification first, followed by Multi-Field (MF) classification which can override the BA result.

Answer

Junos rejects configurations where both BA and MF classifiers are applied to the same interface

Answer

Both classifiers are executed simultaneously in hardware without precedence

Answer

Multi-field classification is evaluated first, followed by behavior aggregate classification

Question 17

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 18

An enterprise design uses PIM sparse-mode with a BSR. An engineer notices that the router has successfully elected a BSR, but no Candidate-RP messages are being processed. Which operational command should the engineer use to verify the BSR candidate information and elected BSR address on the router?

Accepted Answer

show pim bsr statistics. The 'show pim bsr local' or 'show pim bsr' commands display information regarding the BSR state, elected BSR, and received bootstrap messages.

Answer

show igmp bsr

Answer

show msdp bsr-state

Answer

show multicast bsr

Question 19

An enterprise network uses a BGP route reflector (RR) architecture where client routers reflect routes to each other. A non-client router sends a route with an Originator ID and Cluster List to the RR. How does the route reflector handle these attributes when reflecting the route to other clients?

Accepted Answer

It leaves the Originator ID intact and appends its own cluster ID to the Cluster List.. A route reflector leaves the Originator ID untouched and prepends its own Cluster ID to the existing Cluster List to prevent routing loops.

Answer

It removes the Originator ID and replaces the Cluster List with its own cluster ID.

Answer

It increments the Originator ID value by one and clears the Cluster List.

Answer

It clears both the Originator ID and Cluster List to reset loop detection for the local cluster.

Question 20

An EX Series switch is configured with multiple-supplicant mode on an access port connected to an IP phone with a PC daisy-chained behind it. The IP phone authenticates via 802.1X, but the PC uses MAC RADIUS. The phone authenticates successfully and moves to the voice VLAN. However, when the PC boots, it fails authentication because the switch rejects a second supplicant on the same logical port index. Which configuration parameter resolves this issue?

Accepted Answer

Configure the interface with 'set protocols dot1x interface ge-0/0/1 supplicant multiple' and ensure multi-supplicant mode is active.. In multiple-supplicant mode, the switch allows more than one supplicant (e.g., phone and PC) to authenticate independently on the same port. The correct configuration is 'set protocols dot1x interface ge-0/0/1 supplicant multiple' to enable multiple supplicants, and the port must be in multiple-supplicant mode (not single-secure). This allows the phone to authenticate via 802.1X and the PC to authenticate via MAC RADIUS on the same interface.

Answer

Configure 'set access-profile captive-portal multiple-logins per-port'.

Answer

Set the port mode to trunk and enable voice-vlan stacking.

Answer

Configure the interface with 'set protocols dot1x interface ge-0/0/1 mac-radius multiple-clients'.