JNCIP-ENT Practice Test 9 — 10 Questions

Question 1

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?

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

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 2

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 3

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 4

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 5

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 6

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 7

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 8

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 9

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 10

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