JNCIP-ENT Practice Exam 4 — 20 Questions

Question 1

You are configuring MACsec (Media Access Control Security) on an EX Series switch interface to secure Layer 2 links between two enterprise buildings. Which requirement is mandatory for MACsec to establish a secure session successfully between the two switches?

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

Accepted Answer

Both switches must have identical pre-shared keys (connectivity association keys) and matching cipher suites configured.. MACsec requires pre-shared keys (PSK) or MKA (MACsec Key Agreement) with matching connectivity association keys (CAK) and cipher suites.

Answer

Both switches must run RSVP-TE to reserve bandwidth for encrypted frames prior to session establishment.

Answer

Both switches must disable Spanning Tree Protocol on the MACsec-secured interface.

Answer

Both switches must be configured as part of the same VSTP region.

Question 2

Which THREE mechanisms are provided by Juniper switches running MSTP to protect against bridging loops caused by unidirectional link failures or misbehaving switches? (Choose three)

Accepted Answer

Root guard. Loop guard, root guard, and bpdu guard are standard STP/MSTP protection features available on Juniper switches.

Answer

Storm control broadcast filtering

Answer

MACsec cryptographic validation

Question 3

An OSPF area in your network contains multiple ABRs. You need to suppress the generation of Type-4 summary LSAs into a totally stubby area. How does Junos handle this natively?

Accepted Answer

Totally stubby areas automatically block Type-4 LSAs by design without additional configuration.. Totally stubby areas automatically block Type-3, Type-4, and Type-5 LSAs. No separate command is needed to suppress Type-4 LSAs once an area is defined as a totally stubby area.

Answer

You must apply an export policy on the ABR blocking Type-4 LSAs.

Answer

You must use set protocols ospf suppress-fa to remove Type-4 LSAs.

Answer

You must configure set protocols ospf area <area> stub no-summary-asbr.

Question 4

You are troubleshooting MAC address learning on an EX Series switch and want to display dynamic MAC entries learned specifically on interface ge-0/0/5. Which operational command should you use?

Accepted Answer

show bridge mac-table interface ge-0/0/5. The command 'show bridge mac-table interface ge-0/0/5' displays MAC addresses learned on that interface.

Answer

show mac-address-table interface ge-0/0/5

Answer

show ethernet-switching table port ge-0/0/5

Answer

show l2-learning interface ge-0/0/5 macs

Question 5

Which TWO parameters are part of the standard MSTP configuration digest computed across switches in an MST region? (Choose two)

Accepted Answer

MST configuration name. The MST configuration digest includes region name, revision number, and the VLAN-to-instance allocation table.

Answer

Bridge priority value

Answer

Interface MAC addresses

Answer

Hello time and max age timers

Question 6

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 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 TWO statements describe the behavior of VSTP (VLAN Spanning Tree Protocol) on Juniper EX Series switches? (Choose two)

Accepted Answer

VSTP can interoperate with Cisco's PVST+ protocol.. VSTP runs an independent spanning tree instance per VLAN and interoperates with PVST+.

Answer

VSTP is incompatible with RSTP fallback modes.

Answer

VSTP automatically disables all trunk ports if BPDU guard is triggered globally.

Answer

VSTP requires all VLANs to be mapped into a single master MSTI region.

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 EVPN route type is responsible for advertising MAC addresses combined with IP addresses (MAC/IP Advertisement Route)?

Accepted Answer

Route Type 2. Route Type 2 is the MAC/IP Advertisement Route, which carries a MAC address and optionally an IP address, facilitating both L2 bridging and L3 host routing.

Answer

Route Type 3

Answer

Route Type 4

Answer

Route Type 1

Question 11

During a maintenance window, an administrator needs to manually force a Designated Forwarder (DF) role change on a multi-homed Ethernet segment for an EVPN instance. Which parameter must be adjusted to influence the DF election algorithm in Junos OS?

Accepted Answer

Ethernet segment preference value. Junos OS allows influencing the DF election by adjusting the interface preference or local preference values associated with the Ethernet Segment, altering how the DF election algorithm selects the forwarder.

Answer

BGP AS path prepending

Answer

Route Distinguisher value

Answer

Router ID of the BGP speaker

Question 12

Which Junos configuration hierarchy is used to define an EVPN routing instance of type 'evpn'?

Accepted Answer

routing-instances instance-type evpn. In Junos OS, EVPN instances are defined under 'routing-instances instance-type evpn'.

Answer

bridge-domains <name> evpn

Answer

protocols evpn

Answer

interfaces xe-0/0/0 unit 0 family evpn

Question 13

When designing an EVPN-VXLAN fabric with integrated routing and bridging (IRB), which THREE considerations are critical for proper inter-subnet forwarding across VTEPs? (Choose three)

Accepted Answer

Configuring consistent virtual gateway MAC and IP addresses on all IRB interfaces across leaf VTEPs.. Distributed IRB gateways require consistent anycast gateway MAC and IP configurations across all leaf nodes, correct VNI to bridge domain mappings, and EVPN Type-5 or Type-2 route propagation for host/subnet reachability.

Answer

Enforcing physical loopback interfaces to run in layer 2 bridging mode.

Answer

Disabling BGP EVPN signaling on all spine nodes to save CPU resources.

Question 14

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 15

An administrator is deploying EVPN multi-homing with all-active mode on an MX Series router. Which configuration element uniquely identifies the provider edge (PE) router's attachment circuit to an Ethernet segment?

Accepted Answer

Ethernet Segment Identifier (ESI). The Ethernet Segment Identifier (ESI) is a 10-octet unique identifier configured under the interface or access link to identify an Ethernet segment for multi-homing.

Answer

Route Distinguisher (RD)

Answer

Ethernet Tag ID

Answer

ESI Label Extended Community

Question 16

An engineer is verifying MAC learning behavior in an EVPN instance. A remote host's MAC address is learned via BGP Type 2 routes, but when the local host sends traffic to it, the packet drops. The engineer runs 'show route table bgp.evpn.0' and sees the route. What is the most likely reason the packet is dropping in the data plane?

Accepted Answer

The data-plane VNI mapping or tunnel next-hop resolution is incomplete.. Even if the control plane has learned the EVPN Type 2 route, if the data plane tunnel encapsulation (such as a missing VNI mapping or incomplete VXLAN next-hop resolution) is misconfigured, data plane forwarding will fail.

Answer

Type-4 routes have not been exchanged yet.

Answer

The BGP route target import policy is rejecting the route.

Answer

The local router's BGP router ID is misconfigured.

Question 17

Which EVPN route type is responsible for establishing ingress replication lists for Broadcast, Unknown Unicast, and Multicast (BUM) traffic?

Accepted Answer

Route Type 3. Route Type 3 (Inclusive Multicast Ethernet Tag Route) is used to build the peer list for BUM traffic distribution using ingress replication (head-end replication).

Answer

Route Type 5

Answer

Route Type 4

Answer

Route Type 1

Question 18

Which TWO of the following characteristics apply to EVPN Route Type 3 (Inclusive Multicast Ethernet Tag Route)? (Choose two)

Accepted Answer

It carries the originating router's IP address and an Ethernet Tag/VNI identifier.. Route Type 3 routes are used to construct the multicast/broadcast distribution tree using ingress replication (head-end replication) by advertising the PE's IP address and Ethernet tag/VNI.

Answer

It advertises host IP prefixes for inter-subnet routing.

Answer

It dynamically triggers MAC mobility sequence number increments.

Answer

It performs Designated Forwarder election on multi-homed links.

Question 19

Which statement correctly describes the function of an OSPF Stub Area?

Accepted Answer

Stub areas block external AS-external (Type-5) LSAs and use a default route injected by the ABR.. Stub areas block external Type-5 LSAs and instead rely on a default route injected by the ABR.

Answer

Stub areas allow bidirectional redistribution of BGP routes.

Answer

Stub areas block inter-area summary (Type-3) LSAs.

Answer

Stub areas allow Type-7 LSAs from external ASBRs.

Question 20

Which EVPN route type is known as the Ethernet Segment Route and is advertised by a PE router to signal its connectivity to a multi-homed Ethernet segment?

Accepted Answer

Route Type 4. EVPN Route Type 4 is the Ethernet Segment Route, used for discovering other PEs attached to the same Ethernet segment and executing the Designated Forwarder (DF) election.

Answer

Route Type 2

Answer

Route Type 3

Answer

Route Type 1