JNCIP-ENT Practice Test 7 — 10 Questions

Question 1

You need to configure a classifier that inspects the Multiprotocol Label Switching (MPLS) experimental (EXP) bits. Which classifier type must you specify?

Accepted Answer

exp. The MPLS EXP bits are classified using the exp classifier type in Junos CoS configurations.

Answer

fec

Answer

ieee-802.1

Answer

dscp

Question 2

An enterprise WAN edge router running Junos OS has a single 1 Gbps uplink. The design requires that when total egress congestion occurs, the queue carrying business-critical database replication traffic must be guaranteed a minimum of 400 Mbps, while the queue carrying guest internet traffic must never consume more than 200 Mbps even if bandwidth is idle. Which CoS configuration accomplishes this requirement?

Accepted Answer

Apply a transmit-rate of 400m to the critical queue and a shaping-rate of 200m to the guest queue in the scheduler.. Guaranteeing a minimum and enforcing a maximum are distinct scheduler behaviors. A transmit-rate provides the guaranteed minimum share during congestion, whereas a shaping-rate imposes a hard ceiling on how much a queue can transmit even when bandwidth is available. The critical queue needs the guarantee and the guest queue needs the cap, so pairing transmit-rate with shaping-rate matches the design intent.

Answer

Apply a transmit-rate of 400m to the critical queue and a transmit-rate of 200m to the guest queue in the scheduler.

Answer

Apply a shaping-rate of 400m to the critical queue and a transmit-rate of 200m to the guest queue in the scheduler.

Answer

Apply a transmit-rate of 400m with exact to the critical queue and a transmit-rate of 200m with exact to the guest queue in the scheduler.

Question 3

In Junos CoS architecture, what role does a forwarding class play?

Accepted Answer

It represents an internal queue abstraction used to group and process packets. Forwarding classes act as internal labels used by the router to group traffic into specific queues for scheduling and drop treatment.

Answer

It specifies the egress interface physical speed

Answer

It provides static IP routing table entries

Answer

It defines the physical queue index directly on the ASIC

Question 4

An enterprise network uses BGP route reflection. The design team has deployed two route reflectors in the same cluster for redundancy, with all client routers peering to both route reflectors. After a link failure, some clients receive duplicate route advertisements. Which BGP attribute is used to prevent routing loops within a route reflection cluster, and how does it function?

Accepted Answer

CLUSTER_LIST — it records the cluster IDs of route reflectors that a route has traversed, and a route reflector discards a route if its own cluster ID is already present.. The CLUSTER_LIST attribute is the mechanism that prevents routing loops when multiple route reflectors serve the same cluster. Each route reflector prepends its cluster ID to the CLUSTER_LIST when reflecting a route. If a route reflector receives a route that already contains its own cluster ID in the CLUSTER_LIST, it discards the route. This ensures that a route cannot loop back to a route reflector that has already processed it, even if multiple route reflectors exist in the same cluster.

Answer

ORIGINATOR_ID — it identifies the originating router, and a route reflector discards a route if it sees its own router ID as the originator.

Answer

AS_PATH — it records the autonomous systems a route has traversed, and a route reflector discards a route if its own AS number appears in the path.

Answer

MULTI_EXIT_DISC (MED) — it carries metric information and is used to prevent loops by comparing metrics across multiple route reflectors.

Question 5

You are deploying a Juniper EX Series switch as an access layer device in a campus network. The uplink port ge-0/0/1 connects to a distribution switch and is expected to carry traffic for VLANs 10, 20, and 30. You want to prevent the access switch from becoming the root bridge for any of these VLANs and ensure that the uplink is preferred for forwarding. Which configuration should you apply on the access switch?

Accepted Answer

Set the bridge priority to 61440 on the access switch and configure the uplink port with a lower path cost.. To prevent the access switch from becoming the root bridge, a high bridge priority such as 61440 is appropriate. To ensure the uplink is preferred for forwarding, a lower path cost on that port is necessary. Together, these settings control both root bridge election and path selection, aligning with best practices for access layer switches in a campus network.

Answer

Enable RSTP on the access switch and set the uplink port as an edge port to prioritize forwarding.

Answer

Set the bridge priority to 4096 on the access switch and configure the uplink port as the root port using the root-port command.

Answer

Configure the uplink port with a higher path cost and set the bridge priority to 61440 on the access switch.

Question 6

You are configuring a Juniper EX Series switch to support a Layer 2 network with multiple VLANs. You want to use RSTP for faster convergence but need to ensure that each VLAN has its own spanning-tree instance. Which feature should you enable?

Accepted Answer

VSTP. VSTP is the Juniper implementation that runs RSTP per VLAN, providing a separate spanning-tree instance for each VLAN. This meets the requirement of per-VLAN instances with rapid convergence. RSTP and STP use a single instance for all VLANs, and MSTP maps multiple VLANs to a single instance, so they do not provide one instance per VLAN. VSTP is the appropriate feature for this design.

Answer

STP

Answer

RSTP

Answer

MSTP

Question 7

You are deploying a Junos EX Series switch in a campus network. Voice packets arrive untagged from IP phones on access ports, while a trunk uplink carries traffic already marked with DSCP values from the core. You need to ensure that all ingress traffic on the uplink is classified into forwarding classes based solely on the existing DSCP bits without inspecting Layer 3 or Layer 4 headers. Which classifier type should you apply to the uplink interface?

Accepted Answer

Behavior aggregate classifier. Because the incoming packets on the uplink already carry DSCP markings from the core and the goal is to classify them without deeper header inspection, a behavior aggregate classifier is the correct mechanism. BA classifiers map a single CoS field such as DSCP directly to a forwarding class and loss priority, providing efficient, marking-based classification at ingress.

Answer

Fixed classifier

Answer

Multifield classifier

Answer

EXP classifier

Question 8

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 9

A network engineer notices that on a Junos EX Series switch, the voice queue is configured with strict-high priority, but during periods of congestion, data traffic is being dropped while voice traffic is unaffected. The engineer wants to ensure that voice traffic is not only prioritized but also limited so it cannot consume all interface bandwidth. Which scheduler property should be added to the voice queue to cap its maximum transmission rate?

Accepted Answer

shaping-rate. A strict-high priority queue can consume all available bandwidth during congestion, starving lower-priority queues. To prevent this while preserving priority servicing, the shaping-rate property must be configured on the voice queue to enforce a maximum transmission rate. This caps the voice queue's consumption and protects other traffic.

Answer

transmit-rate

Answer

buffer-size

Answer

excess-rate

Question 10

You are deploying a Junos device where a single physical interface carries both a latency-sensitive multicast video stream and best-effort file transfers. You must ensure that the video traffic is transmitted with the lowest possible per-hop latency and jitter, even when the best-effort queue is congested, without starving the other queues. Which CoS feature should you configure on the egress interface to meet this requirement?

Accepted Answer

A strict-high priority scheduler applied to the video forwarding class queue. Strict-high priority scheduling is the only Junos scheduler property that guarantees a queue is serviced ahead of all others when packets are present, which is exactly what latency-sensitive multicast video requires under congestion. Weighted scheduling, low-priority scheduling, and policing all address bandwidth allocation or rate limiting rather than strict preferential transmit ordering, so they cannot provide the lowest per-hop latency and jitter.

Answer

A low-priority scheduler with a large buffer size on the video queue

Answer

A weighted round-robin scheduler with a high transmit-rate on the video queue

Answer

A rate-limited policer applied to the video forwarding class