JNCIP-ENT Practice Test 12 — 15 Questions

Question 1

When configuring OSPF sham-links in Junos to support MPLS VPN back-door links, which TWO characteristics apply? (Choose two)

Accepted Answer

Sham-links are configured as point-to-point links between PE router loopback addresses within the VPN routing instance.. Sham-links are treated as intra-area links between PE routers and require a separate /32 IP address configured under the loopback or routing instance, appearing as unnumbered or numbered point-to-point links.

Answer

Sham-links are advertised as Type-5 external LSAs across the network.

Answer

Sham-links require physical interfaces dedicated solely to the backdoor connection.

Answer

Sham-links are only supported in OSPFv3, not OSPFv2.

Question 2

When configuring EVPN multi-homing in all-active mode, which THREE key components or concepts must be properly established across the PE routers? (Choose three)

Accepted Answer

A Designated Forwarder (DF) election mechanism using Type-4 routes to determine who forwards BUM traffic.. EVPN all-active multi-homing requires a consistent Ethernet Segment Identifier (ESI) across participating PEs, an active Designated Forwarder election (governed by Type-4 routes), and split-horizon filtering to prevent traffic loops.

Answer

Enabling Spanning Tree Protocol root bridge on all leaf nodes.

Answer

Configuring OSPF as the underlay routing protocol for EVPN signaling.

Question 3

Which standard Junos forwarding class is reserved for control plane traffic such as routing protocols and management traffic?

Accepted Answer

network-control. In Junos, the network-control forwarding class is reserved for control plane traffic to ensure it receives priority handling.

Answer

expedited-forwarding

Answer

assured-forwarding

Answer

best-effort

Question 4

A Junos router connects to a Layer 2 switch that has multiple receivers on VLAN 200. The switch is not running PIM, and the router is the only multicast router on the segment. You want the router to send IGMP general queries on the VLAN 200 interface and track receiver group memberships. Which configuration is required?

Accepted Answer

Enable IGMP on the VLAN 200 interface with a version compatible with the receivers.. The router must run IGMP on the interface that faces the receivers to act as the querier and maintain group membership state. IGMP queries solicit reports, and the reports populate the membership database that drives PIM joins. PIM alone does not perform this signaling, and IGMP snooping is a switch-side optimization, so IGMP on the interface with a matching version is the required configuration.

Answer

Configure a static multicast route for 224.0.0.0/4 pointing out the VLAN 200 interface.

Answer

Enable PIM sparse-mode on the VLAN 200 interface and configure an RP.

Answer

Enable IGMP snooping on the router's VLAN 200 interface.

Question 5

Which RADIUS attribute is commonly used to assign a specific session timeout value to an 802.1X authenticated client on an EX Series switch?

Accepted Answer

Session-Timeout (Attribute 27). RADIUS Attribute 27 (Session-Timeout) specifies the maximum number of seconds of service to be provided to the user.

Answer

Idle-Timeout (Attribute 28)

Answer

Tunnel-Client-End-Id (Attribute 66)

Answer

Termination-Action (Attribute 29)

Question 6

An engineer is troubleshooting a BGP route reflection topology where a non-client IBGP peer sends a route to a route reflector. Will the route reflector reflect this route to other non-client IBGP peers?

Accepted Answer

No, routes received from a non-client peer are only reflected to client peers, not to other non-client peers.. A route reflector reflects routes from clients to clients, clients to non-clients, and non-clients to clients, but it does NOT reflect routes received from a non-client to other non-client peers.

Answer

Yes, all routes received by a route reflector are reflected to all peers regardless of client status.

Answer

No, route reflectors never reflect routes received from any IBGP peer.

Answer

Yes, provided the routes contain the same Cluster ID as the receiving non-client peer.

Question 7

You notice that an EX4300 switch power budget calculation is set to use 'class-based' allocation. What does this mean regarding how power is reserved for connected IP phones?

Accepted Answer

The switch reserves power according to the maximum wattage defined by the device's hardware PoE class (e.g., Class 0, Class 3).. Class-based power allocation reserves the maximum wattage specified by the device's 802.3af/at power class, regardless of actual consumption.

Answer

The switch allocates a flat 15.4W to every port regardless of what device is plugged in.

Answer

The switch shares a dynamic pool where ports draw power on a first-come, first-served basis without limits.

Answer

The switch allocates power based on real-time LLDP-MED reported consumption values.

Question 8

When troubleshooting EVPN control plane connectivity in Junos OS, which THREE commands provide essential diagnostic information regarding EVPN routing tables and peers? (Choose three)

Accepted Answer

show route table bgp.evpn.0. To troubleshoot EVPN control plane issues, commands like 'show route table bgp.evpn.0', 'show bgp summary', and 'show evpn database' are essential for verifying route tables, neighbor status, and MAC databases.

Answer

show mpls lsp extensive

Answer

show spanning-tree interface

Question 9

Which TWO of the following statements accurately describe EVPN Route Type 2 (MAC/IP Advertisement Route)? (Choose two)

Accepted Answer

It can carry both a MAC address and an IP address in a single control-plane update.. Type 2 routes advertise MAC addresses and optionally host IP addresses. They play a critical role in both Layer 2 bridging and Integrated Routing and Bridging (IRB) host reachability.

Answer

It is exclusively used to elect the Designated Forwarder for multicast traffic.

Answer

It is only generated when BUM traffic flooding occurs.

Answer

It replaces BGP L3VPN route targets for core routing.

Question 10

In a Juniper Virtual Chassis scaling deployment comprising 10 EX4600 switches, how are control and management planes structured across member switches to maintain high availability and failover resilience?

Accepted Answer

Two switches are elected as Master and Backup Routing Engines, while remaining switches act as line cards.. A Virtual Chassis designates a Routing Engine (RE) Master and Backup across designated members, while all switches participate in the distributed forwarding plane.

Answer

Every switch runs its own independent Spanning Tree instance to prevent loops across the virtual backplane.

Answer

Control traffic is load-balanced across all 10 member switches using ECMP across the dedicated stacking ports.

Answer

All 10 switches run independent routing engines with separate control planes and synchronized MAC tables.

Question 11

An EX Series switch is configured with 802.1X and MAC RADIUS. A client device connects that does not support 802.1X. The switch attempts 802.1X, times out, and successfully falls back to MAC RADIUS. However, the administrator notices a significant delay (several seconds) before the MAC RADIUS request is sent to the server. What parameter should be tuned to reduce this delay?

Accepted Answer

Reduce the 'supp-timeout' and 'max-retries' parameters under the 802.1X interface configuration.. The delay occurs because the switch first attempts 802.1X authentication, which times out after a period determined by the 'supp-timeout' (supplicant timeout) and 'max-retries' parameters. These control how long the switch waits for an EAPOL response from the client and how many retries it sends before giving up and falling back to MAC RADIUS. Reducing these values shortens the 802.1X attempt phase, allowing the switch to move to MAC RADIUS faster. Thus, tuning 'supp-timeout' and 'max-retries' directly addresses the observed delay.

Answer

Increase the 'server-timeout' parameter in the access-profile configuration.

Answer

Disable EAPOL-start message generation on the switch port.

Answer

Enable fast-reauth under the system authentication options.

Question 12

Which THREE parameters are typically included in an LLDP-MED network policy TLV for voice application? (Choose three.)

Accepted Answer

VLAN ID. The LLDP-MED Network Policy TLV for a voice application carries the parameters a VoIP endpoint needs to tag its traffic correctly: option A (VLAN ID) tells the phone which voice VLAN to use, option D (DSCP Value for Layer 3 QoS) provides the Layer 3 marking the phone should apply to voice RTP/signaling, and option E (Layer 2 Priority, 802.1p) supplies the CoS value for the 802.1Q tag. These three fields—VLAN ID, Layer 2 priority, and DSCP—are the standard contents of the Network Policy TLV defined in ANSI/TIA-1057 for LLDP-MED, along with an application type and unknown-policy flag. Option B (IP Phone MAC Address) is not part of the policy TLV; the phone's MAC is learned via normal source-MAC learning or the LLDP chassis ID, not advertised as a policy parameter. Option C (Switch Power Supply Serial Number) is unrelated to QoS/VLAN policy and would only appear in inventory or power-management contexts, not in a network policy TLV.

Answer

IP Phone MAC Address

Answer

Switch Power Supply Serial Number

Question 13

An enterprise network uses 802.1X authentication with dynamic VLAN assignment on EX Series switches. A client authenticates, and the RADIUS server returns both a VLAN name and a set of dynamic firewall filter names via RADIUS attributes (Filter-Id). When the client connects, the VLAN assignment works perfectly, but the firewall filters are not applied to the interface. What is the most likely cause?

Accepted Answer

The named firewall filters were not pre-configured and committed locally on the EX Series switch.. For dynamic Filter-Id attributes returned by RADIUS to be applied successfully on an EX Series switch, the named firewall filters must already be pre-configured and committed locally on the switch. If the filter does not exist locally, the application fails.

Answer

The dynamic filter must be defined inside the global access profile instead of being returned by RADIUS.

Answer

RADIUS Filter-Id attributes are not supported on EX Series switches for dynamic firewall application.

Answer

Dynamic filter assignment requires MAC RADIUS and is not supported with 802.1X.

Question 14

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 15

An engineer needs to ensure that a Junos router balances BGP traffic across multiple paths with unequal IGP costs. Which feature must be configured to achieve this?

Accepted Answer

BGP multipath with the 'as-path-relax' or equivalent multipath options enabled.. By default, BGP multipath requires equal cost. To allow paths with different costs, 'as-path-multipath' or variance-based multipath configurations are required depending on specific Junos platform support, but generally standard multipath requires equal IGP cost unless specific multipath relaxation options are set.

Answer

Setting the MED attribute to zero on all incoming EBGP updates.

Answer

Configuring static routes with identical preferences for every BGP prefix.

Answer

Enabling BGP Route Reflection on the local routing engine.