JNCIP-ENT Practice Test 4 — 25 Questions

Question 1

A Junos router is the last-hop router for receivers in VLAN 100. The receivers use IGMPv3 and request group 239.5.5.5 from source 10.10.10.10 only. The router has a PIM sparse-mode shared tree (*,G) toward the RP, but traffic from 10.10.10.10 is not being delivered to the receivers. The unicast route to 10.10.10.10 points out a different interface than the one toward the RP. Which action resolves the problem?

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

Accepted Answer

Ensure PIM is enabled on the interface toward 10.10.10.10 so the router can build the (S,G) tree.. When a receiver requests a specific source and group, the last-hop router must create (S,G) state and send a PIM join toward the source using the unicast route to the source address. That route can differ from the path toward the rendezvous point. If PIM is not enabled on the outgoing interface toward the source, the join cannot be sent and traffic is never forwarded, so PIM must be enabled on that interface.

Answer

Add a static IGMP group membership for 239.5.5.5 on the VLAN 100 interface.

Answer

Configure an RP for the group so the shared tree can be used for delivery.

Answer

Increase the IGMP query interval on VLAN 100 so the receiver reports are refreshed more often.

Question 2

You are troubleshooting an OSPF network where a Juniper router is not installing a particular OSPF route into its routing table. The route is present in the OSPF link-state database as an external LSA, but it is not in the inet.0 table. You have verified that the route is not filtered by any policy. What is the most likely cause?

Accepted Answer

The external LSA has a forwarding address that is unreachable.. The forwarding address in an external LSA must be reachable for OSPF to install the route. If it is not, the route remains in the LSDB but is not used. This is a common troubleshooting point for OSPF external routes.

Answer

The OSPF route preference is lower than another protocol's route.

Answer

The OSPF area is a stub area, which blocks external LSAs.

Answer

The OSPF router ID is not configured.

Question 3

You are configuring captive portal on an EX Series switch. Users must be redirected to an external web server for authentication. You have configured the captive portal profile with the redirect URL. However, users are not being redirected and can access the Internet without authentication. Which configuration issue is most likely?

Accepted Answer

The captive portal profile is not applied to the interface.. Captive portal requires the profile to be applied to the interface. Without this, the switch does not intercept HTTP traffic and redirect users to the authentication page. The redirect URL alone is insufficient; the profile must be bound to the interface to activate the feature.

Answer

The 'authentication-order' is set to 'radius' instead of ' captive-portal'.

Answer

The 'interface-mode' is set to trunk instead of access.

Answer

The 'redirect-url' is not configured under the captive portal profile.

Question 4

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 5

Which Junos configuration hierarchy is used to define a BGP peer group to simplify neighbor configurations?

Accepted Answer

protocols bgp group <group-name>. BGP peer groups and neighbor settings are configured under the 'protocols bgp group' hierarchy in Junos.

Answer

routing-options autonomous-system

Answer

interfaces <interface-name> unit 0 family inet bgp

Answer

policy-options community

Question 6

You need to design a scalable Layer 2 architecture across multiple data center buildings using Juniper switches, avoiding single points of failure while preventing bridging loops. Which scaling mechanism allows Active-Active multihoming without running Spanning Tree Protocol across the core?

Accepted Answer

Multi-Chassis Link Aggregation (MC-LAG) with ICCP. MC-LAG (Multi-Chassis Link Aggregation Group) or EVPN-VXLAN provides active-active multihoming and eliminates spanning tree loops. Among traditional Layer 2 tools, MC-LAG is the direct multi-chassis active-active solution.

Answer

Layer 2 Tunneling Protocol (L2TPv3) bridging

Answer

Rapid PVST+ with root guard on all access ports

Answer

Virtual Chassis with spanning-tree disabled

Question 7

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 8

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 9

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 10

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 11

An enterprise design requires configuring an Anycast RP setup using two Junos routers to provide redundancy for PIM sparse-mode. Which mechanism is required to synchronize source state information between the two Anycast RPs within the same AS?

Accepted Answer

Multicast Source Discovery Protocol (MSDP). When deploying Anycast RP within a single PIM domain using MSDP, MSDP peer connections are established between the Anycast RP addresses to exchange SA (Source Active) messages, ensuring both RPs know about sources registered to either RP.

Answer

Protocol Independent Multicast Dense-Mode (PIM-DM)

Answer

IGMPv3 snooping

Answer

Multicast BGP (MBGP)

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 are configuring OSPF database overflow protection to prevent a router from running out of memory due to an excessive number of external LSAs in the LSDB. Which configuration enables this feature globally?

Accepted Answer

set protocols ospf database-overflow limit 5000 external-timer 300. Database overflow protection in Junos OSPF is configured using the 'database-overflow' statement under protocols ospf, specifying the limit and external timer.

Answer

set protocols ospf max-external-lsas 5000

Answer

set protocols ospf area 0.0.0.0 overflow-limit 5000

Answer

set routing-options ospf overflow-protection limit 5000

Question 14

An enterprise network administrator needs to configure 802.1X authentication on EX Series switches. Which statement is correct regarding the default behavior of the supplicant timeout timer?

Accepted Answer

It defines the duration the switch waits for an EAP-Request/Identity frame response before retransmitting.. In Junos 802.1X, the supplicant timeout timer defines how long the switch waits for a response to an EAP-Request/Identity frame before retransmitting it. This timer is part of the EAPOL handshake and ensures the switch does not wait indefinitely for a supplicant that is slow or unresponsive. It is not related to MAC RADIUS failover, idle disconnect, or RADIUS session teardown.

Answer

It dictates how long the switch waits before failing over to MAC RADIUS authentication.

Answer

It determines how long an authenticated client can remain idle before being disconnected.

Answer

It specifies the interval before the switch drops the entire RADIUS authentication session.

Question 15

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 16

Which THREE parameters must be configured when implementing captive portal on an EX Series switch? (Choose three)

Accepted Answer

A captive portal profile specifying redirection URLs and authentication parameters.. Option A is correct because a captive portal profile is the core configuration object that defines the redirection URL (the web page clients are sent to), the authentication parameters, and the associated access profile used to authenticate users. Option C is correct because the captive portal service must be bound to specific interfaces or VLANs so the switch knows which ingress traffic triggers the portal interception and redirection. Option E is correct because an access profile defines the authentication server group (RADIUS/LDAP) and the authentication order that the captive portal uses to validate user credentials. Option B is incorrect because a global RADIUS accounting policy with interim-interval set to zero is not required for captive portal; accounting is optional and unrelated to portal redirection. Option D is incorrect because captive portal on EX Series switches does not require a static NAT pool to translate client IPs to the portal server IP; redirection is handled by the switch's captive portal mechanism, not NAT.

Answer

A global RADIUS accounting policy with interim-interval set to zero.

Answer

A static NAT pool for translating client IP addresses to the captive portal server IP.

Question 17

A network administrator needs to display the multicast routing table entries, including incoming interfaces and outgoing interface lists (OIL), on a Junos device. Which operational command should be used?

Accepted Answer

show multicast route. The 'show multicast route' command displays the Multicast Forwarding Information Base (MFIB) entries, including source, group, incoming interface, and outgoing interfaces.

Answer

show ospf route

Answer

show igmp interface

Answer

show pim join

Question 18

Which Junos configuration command enables MD5 cryptographic authentication on an OSPFv2 interface?

Accepted Answer

set protocols ospf area 0.0.0.0 interface ge-0/0/0.0 authentication md5 1 key "secret". MD5 authentication for OSPFv2 in Junos is configured under the interface hierarchy with the 'authentication md5' statement followed by a key ID and password.

Answer

set security ospf md5 interface ge-0/0/0.0 key "secret"

Answer

set protocols ospf area 0.0.0.0 interface ge-0/0/0.0 md5-password "secret"

Answer

set protocols ospf area 0.0.0.0 interface ge-0/0/0.0 authentication-type md5

Question 19

You are configuring Ethernet switching on an EX4300 switch and need to implement storm control to prevent broadcast, multicast, and unknown unicast traffic from overwhelming access links. Where is storm-control applied in the Junos configuration hierarchy?

Accepted Answer

set interfaces ge-0/0/1 unit 0 family ethernet-switching storm-control. Storm control is applied under 'interfaces <interface-name> unit 0 family ethernet-switching storm-control'.

Answer

set vlans default storm-control

Answer

set protocols l2-learning storm-control interface ge-0/0/1

Answer

set forwarding-options storm-control interface ge-0/0/1

Question 20

You want to map three loss priorities (low, medium-low, high) to different drop profiles within a specific forwarding class. Which statement should you use inside the scheduler configuration?

Accepted Answer

drop-profile-map. In Junos scheduler configurations, drop-profile-map associates a loss priority and forwarding class with a specific drop profile.

Answer

classifier-map

Answer

loss-priority-mapping

Answer

queue-drop-profile