JNCIP-ENT Multiple Select — 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

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 4

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 5

Which TWO of the following statements correctly describe the operation and benefits of EVPN MAC mobility? (Choose two)

Accepted Answer

It uses sequence numbers attached to Type-2 routes to track host movement between different PEs.. EVPN MAC mobility uses sequence numbers in the MAC Mobility Extended Community to detect when a host moves between PEs, preventing blackholing and updating forwarding tables correctly.

Answer

It forces BGP session resets whenever a MAC address moves between subnets.

Answer

It is exclusively used for Route Type 4 Designated Forwarder election.

Answer

It requires Spanning Tree Protocol to be enabled to detect host migration.

Question 6

Which TWO actions can be performed by an OSPF routing policy export filter when redistributing routes into OSPF? (Choose two)

Accepted Answer

Modify the OSPF route metric using the metric action.. Routing policies when exporting into OSPF can set metric types (Type 1 or Type 2) and modify route metrics. They cannot directly change area ID during redistribution without area design changes.

Answer

Change the OSPF hello timer interval via routing policy.

Answer

Alter the OSPF router ID of neighboring routers.

Answer

Change the OSPF area ID of external routes dynamically.

Question 7

When configuring advanced Q-in-Q tunneling on Juniper MX Series routers, which THREE encapsulation or tagging parameters must be correctly aligned between the customer edge and provider edge interfaces? (Choose three)

Accepted Answer

VLAN action rules (pop, push, or swap). Q-in-Q alignment requires matching flexible-vlan-tagging, TPID values (EtherType), and VLAN tag preservation/manipulation rules.

Answer

MSTP region name configuration

Answer

IGMP snooping version compatibility

Question 8

Which THREE configuration tasks are required when implementing OSPFv3 on Junos devices? (Choose three)

Accepted Answer

Enabling OSPFv3 under the protocols ospf3 hierarchy. Configuring OSPFv3 requires specifying protocols ospf3, configuring areas, and enabling OSPFv3 on specific interfaces (IPv6 enabled).

Answer

Configuring BGP autonomous system numbers for OSPFv3 operation

Answer

Enabling IPv4 address families inside protocols ospf3

Question 9

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 10

Which TWO options are valid authentication methods that can be specified in the 'authentication-order' statement on an EX Series switch interface? (Choose two)

Accepted Answer

mac-radius. On Juniper EX Series switches, the 'authentication-order' statement under an interface (or globally) accepts authentication methods such as 'dot1x', 'mac-radius', and 'captive-portal'. Option D (dot1x) is correct because IEEE 802.1X is a supported access-control authentication method that can be listed in the authentication order to authenticate supplicants via an AAA server. Option A (mac-radius) is correct because MAC RADIUS authentication is also a supported method, allowing the switch to authenticate a device by its MAC address against a RADIUS server. Option B (kerberos) is not a valid authentication-order method on EX switches, as Kerberos is not implemented as an interface authentication method there. Option C (tacacs-plus) is not valid because TACACS+ is an AAA protocol used for administrative login/authorization, not a client authentication method in the interface authentication-order list. Option E (ldap-direct) is not valid because EX switches do not support a direct LDAP authentication method in the authentication-order statement; LDAP would be reached through a RADIUS server instead.

Answer

kerberos

Answer

tacacs-plus

Answer

ldap-direct

Question 11

Which THREE parameters are part of the standard Junos BGP route selection algorithm prior to evaluating the router ID? (Choose three)

Accepted Answer

Weight (local to the router). Before router ID, Junos evaluates Weight, Local Preference, AS path length, Origin, MED, and IBGP vs EBGP preference.

Answer

Cluster List length

Answer

Originator ID value

Question 12

An engineer is troubleshooting a multicast forwarding issue where data from a specific source is not reaching receivers in a remote PIM sparse-mode domain. Which THREE operational commands and diagnostic steps should be used to verify the multicast forwarding state and RPF path on a Junos router? (Choose three)

Accepted Answer

Run 'show pim join' to inspect upstream neighbor information and verify the RPF interface for the source.. Option B is correct because 'show pim join' displays the PIM join state, including the upstream neighbor (RPF neighbor) and the incoming/RPF interface for each (S,G) or (*,G) entry, which is exactly what is needed to confirm the RPF path toward the source in a PIM sparse-mode domain. Option C is correct because 'show igmp group' verifies that receivers on the local segment have actually sent IGMP joins for the group, confirming the last-hop router has the group membership needed to build the multicast forwarding state. Option E is correct because 'show multicast route' shows the installed (S,G)/(*,G) forwarding entries along with their incoming and outgoing interfaces and packet counters, letting the engineer confirm whether traffic is being forwarded and where it may be dropping. Option A is not correct because OSPF LSA type 6 (group-membership LSA) is MOSPF-specific and is not used for RPF checks in a PIM sparse-mode domain. Option D is not correct because there is no 'show bgp summary multicast-unicast' command, and multicast RPF lookups in Junos use the unicast routing table (inet.0) or an explicit multicast RPF table, not a BGP multicast-unicast summary.

Answer

Run 'show ospf database multicast' to verify LSA type 6 propagation.

Answer

Run 'show bgp summary multicast-unicast' to verify BGP routing tables for multicast RPF checks.

Question 13

Which TWO commands are used to troubleshoot OSPF issues on Junos devices? (Choose two)

Accepted Answer

show ospf neighbor. Operational commands like 'show ospf neighbor' and 'show ospf database' are standard for troubleshooting OSPF adjacencies and LSDB status.

Answer

show ip ospf interface

Answer

show protocols ospf status

Answer

show route ospf-table

Question 14

Which TWO statements describe the function and operation of a PIM Bootstrap Router (BSR)? (Choose two)

Accepted Answer

The BSR collects Candidate-RP messages and periodically distributes the RP-set to all PIM routers.. The BSR collects Candidate-RP advertisements and distributes the RP-set to all routers in the domain via bootstrap messages.

Answer

The BSR acts as the data encapsulation point for multicast sources.

Answer

The BSR forwards multicast data packets directly to receivers.

Answer

The BSR is required to establish MSDP sessions between autonomous systems.

Question 15

You are configuring an EX Series switch to support IP phones that use LLDP-MED for network policy. Which two statements are true about LLDP-MED network policy TLVs? (Choose two.)

Accepted Answer

They can specify the Layer 2 priority and DSCP values for QoS.. LLDP-MED network policy TLVs are sent by the switch to the phone and include VLAN ID, Layer 2 priority, and DSCP values. These parameters allow the phone to configure its VLAN and QoS settings automatically. They are not sent by the phone, can be used for multiple application types, and require LLDP to be enabled.

Answer

They are sent by the phone to the switch to request VLAN assignment.

Answer

They are only used for voice applications and not for other media types.

Answer

They require LLDP to be disabled to function properly.

Question 16

Which TWO statements describe the characteristics of Random Early Detection (RED) and drop profiles in Junos? (Choose two)

Accepted Answer

Drop profile curves plot drop probability against queue buffer fill level. Drop profiles define drop probability against fill level, helping prevent TCP global synchronization.

Answer

Drop profiles are configured under the forwarding-classes hierarchy

Answer

Drop profiles drop 100% of packets immediately once the queue fill level reaches the start point

Answer

Drop profiles operate exclusively on Layer 2 control frames

Question 17

Which THREE statements describe the behavior of critical authentication (fallback) when a RADIUS server becomes unreachable on an EX Series switch? (Choose three)

Accepted Answer

The switch moves authenticating clients into a designated critical VLAN or applies a critical profile.. Option A is correct because when critical authentication (fallback) is triggered by an unreachable RADIUS server, the EX Series switch places newly authenticating supplicants into a preconfigured critical VLAN (or applies a critical profile), granting limited access until the server is reachable again. Option C is correct because Juniper EX switches allow critical authentication to be configured independently for 802.1X and MAC RADIUS authentication, so each method can have its own critical VLAN/profile settings. Option E is correct because the switch periodically re-probes the primary RADIUS servers at configured intervals (via the server-reject/retry timers) so it can detect recovery and move clients back to normal authenticated state. Option B is wrong because the local user database is never deleted during RADIUS failure; it is retained and used only if local authentication fallback is configured. Option D is wrong because already-authenticated clients are not immediately disconnected when the RADIUS server becomes unreachable; they remain authenticated until reauthentication or session timeout.

Answer

The local switch user database is permanently deleted to save memory during server failure.

Answer

Clients that are already successfully authenticated are immediately disconnected and forced to re-authenticate.

Question 18

Which TWO operational commands are valid for troubleshooting VSTP on Juniper EX switches? (Choose two)

Accepted Answer

show vstp vlan. show vstp and show vstp vlan are valid operational commands for VSTP.

Answer

show vstp topology-change

Answer

show spanning-tree vstp-status

Answer

show ethernet-switching vstp-neighbors

Question 19

Which TWO of the following statements regarding EVPN Route Type 1 (Ethernet Auto-Discovery Route) are correct? (Choose two)

Accepted Answer

Type 1 routes are advertised either per-EVI or per-Ethernet Segment (ES).. Route Type 1 comes in two variants: per-EVI and per-ES. Per-EVI routes provide aliasing for load-balancing across multi-homed PEs, and per-ES routes facilitate fast convergence during node failures.

Answer

Type 1 routes are only used in single-homed network topologies.

Answer

Type 1 routes are exclusively used for mapping IP prefixes to IP-VRFs.

Answer

Type 1 routes replace Type 3 routes for handling BUM traffic replication.

Question 20

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.