JNCIP-ENT Practice Questions 1 — 50 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

Which THREE actions can be executed by a firewall filter policer when traffic exceeds the specified rate? (Choose three)

Accepted Answer

discard. In Junos firewall filter policers, the three valid actions that can be configured when traffic exceeds the specified rate are discard, loss-priority high, and forward. Option A (discard) is correct because the policer can simply drop out-of-profile packets, which is the most common bandwidth-limiting behavior. Option B (loss-priority high) is correct because the policer can mark excess packets with a high loss priority so downstream congestion-management (RED/WRED) drops them preferentially instead of dropping them immediately. Option D (forward) is correct because the policer can pass out-of-profile packets through while optionally setting a loss priority, allowing later devices or schedulers to handle them. Option C (reroute-lsp) is not a policer action; it is an MPLS routing action used in routing policies or forwarding-adjacency contexts, not in a policer's then statement. Option E (queue-switch) is not a valid policer action either; queue selection is handled by forwarding classes and schedulers, not by policers.

Answer

reroute-lsp

Answer

queue-switch

Question 3

An engineer notices that a Junos device is not installing a BGP route into the forwarding table because the BGP next hop is unresolved. Which tool or command can be used to troubleshoot how the BGP next hop is being resolved in the Junos routing table?

Accepted Answer

show route resolution. To check BGP next-hop resolution, the 'show route resolution' command displays how next hops are resolved via the routing table (RIB-local), showing whether an active IGP or static route covers the BGP next-hop IP address.

Answer

show bgp summary

Answer

show bgp group

Answer

show route advertising-protocol bgp

Question 4

What is the primary function of the RADIUS server attribute 'Tunnel-Medium-Type' (Attribute 65) when received during an 802.1X authentication exchange on an EX Series switch?

Accepted Answer

It specifies the physical transport media type for the tunnel, such as 802 (Ethernet) for VLAN assignment.. Tunnel-Medium-Type specifies the media type of the tunnel, which for VLAN assignments in Junos is typically set to 802 (Ethernet).

Answer

It defines the VLAN ID or VLAN name to which the authenticated client port should be dynamically assigned.

Answer

It determines the encryption cipher used between the switch and the RADIUS server.

Answer

It indicates the authentication protocol (PAP, CHAP, EAP) being used in the tunnel.

Question 5

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 6

A network engineer is configuring class of service on a Junos switch and wants to guarantee that the network control traffic forwarding class always has bandwidth available for routing protocol updates, even during heavy data congestion. The engineer also wants to ensure that this class is not starved by other queues. Which scheduler configuration should the engineer apply to the network control forwarding class?

Accepted Answer

A scheduler with a guaranteed transmit-rate and a high priority. A guaranteed transmit-rate reserves bandwidth for the network control forwarding class, and high priority ensures it is serviced ahead of ordinary data queues, protecting routing protocol updates during congestion without the starvation risk of strict-high priority. Low priority, excess-only rates, and strict-high with policing all fail to provide the required balance of guaranteed bandwidth and preferential servicing.

Answer

A scheduler with a strict-high priority and a policer to cap its rate

Answer

A scheduler with a low priority and a small buffer size

Answer

A scheduler with an excess transmit-rate and a low priority

Question 7

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 8

When configuring OSPFv3, which Junos address-family hierarchy is used to enable OSPFv3 on an interface?

Accepted Answer

set protocols ospf3 area 0.0.0.0 interface xe-0/0/0.0. OSPFv3 in Junos operates within the IPv6 address family under protocols ospf3.

Answer

set protocols ospf version 3 area 0.0.0.0 interface xe-0/0/0.0

Answer

set protocols ipv6 ospf area 0.0.0.0 interface xe-0/0/0.0

Answer

set protocols ospf3 ipv6 area 0.0.0.0 interface xe-0/0/0.0

Question 9

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 10

An administrator wants to configure an MSDP peer relationship on a Junos device and ensure that the MD5 password authentication is applied to the TCP session. Where is the MD5 authentication key configured for an MSDP peer?

Accepted Answer

set protocols msdp peer

authentication-key . MSDP authentication keys are configured under the specific MSDP peer statement using the authentication-key option.

Answer

set system authentication-key <key>

Answer

set protocols pim peer

authentication-key

Answer

set routing-options msdp authentication-key <key>

Question 11

When configuring a BGP route reflector cluster in Junos, which THREE guidelines or operational behaviors should an engineer keep in mind? (Choose THREE)

Accepted Answer

A route reflector must never reflect routes received from a non-client peer back to other non-client peers.. Route reflectors reflect routes between clients and non-clients. Loop prevention uses Originator ID and Cluster List. Redundant RRs in the same cluster must share the same cluster ID to prevent routing loops and oscillation.

Answer

Clients of a route reflector must be configured in a full iBGP mesh with each other.

Answer

Route reflectors automatically modify the AS_PATH attribute of all reflected routes.

Question 12

A network engineer has configured BGP multipath on a Junos routing device using the 'multipath' statement under the routing-options bgp hierarchy. However, traffic is still only utilizing a single path. Which condition must be met for BGP multipath to become active for a destination prefix?

Accepted Answer

All competing BGP paths must have identical AS path lengths, local preference, origin, and MED.. For BGP multipath to be valid in Junos, the paths must have matching AS path lengths, local preferences, origins, and MEDs, along with valid next-hop resolution through the IGP.

Answer

Multipath requires BGP prefix-independent convergence (PIC) to be explicitly enabled on all routing engines.

Answer

The next hops must be directly connected interfaces without relying on IGP resolution.

Answer

All paths must originate from the exact same autonomous system in the AS path attribute.

Question 13

You are configuring Q-in-Q tunneling on an MX Series router where customer frames arrive with VLAN tag 100, and you need to encapsulate them with a service provider outer VLAN tag 3000 using 'vlan-map'. Where is the VLAN map applied?

Accepted Answer

Under the logical interface unit configuration using input/output vlan-map. VLAN maps or rewriting rules are applied on the logical interface (subinterface) inbound or outbound directions.

Answer

Under the routing-instance bridge-domain configuration

Answer

Under protocols l22-control configuration hierarchy

Answer

Under the physical interface encapsulation statement

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

A network designer needs to implement BGP route reflection where multiple route reflectors are deployed in the same cluster to provide redundancy. What parameter must be identical across all route reflectors in that same cluster to prevent routing loops?

Accepted Answer

Cluster ID. Route reflectors within the same cluster must share the same Cluster ID so they can recognize and ignore routes reflected by their peer route reflector.

Answer

AS Path Prepend count

Answer

Local Preference value

Answer

Router ID

Question 16

An administrator wants to configure MSDP (Multicast Source Discovery Protocol) between two autonomous system border routers to share active source information. Which configuration hierarchy in Junos is used to define the MSDP peer relationship?

Accepted Answer

[edit protocols msdp]. MSDP in Junos is configured under the [edit protocols msdp] hierarchy.

Answer

[edit routing-options msdp]

Answer

[edit protocols pim msdp]

Answer

[edit protocols bgp group msdp]

Question 17

You have configured a custom scheduler map, but traffic in the best-effort queue is being starved during periods of heavy congestion. Which scheduler parameter should you adjust to guarantee a minimum bandwidth for this queue?

Accepted Answer

transmit-rate. The transmit-rate parameter in a scheduler definition guarantees a minimum bandwidth allocation for a queue even during congestion.

Answer

drop-profile-map

Answer

buffer-size temporal

Answer

priority high

Question 18

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 19

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 20

Which statement accurately describes the function of the 'server-timeout' setting within a Juniper access profile?

Accepted Answer

It defines how long the switch waits for a reply from the RADIUS server before failing over to the next server.. The server-timeout setting determines how long the switch waits for a response from a RADIUS server before trying the next server in the server group.

Answer

It determines the maximum duration a client session can remain active before forced re-authentication.

Answer

It dictates the interval at which the switch sends RADIUS accounting interim updates.

Answer

It specifies the idle timeout period for disconnected supplicants.