JNCIS-ENT Practice Test 4 — 10 Questions

Question 1

An engineer is configuring static routes in Junos OS and wants to ensure high availability. Which TWO features can be implemented with static routes to achieve path redundancy? (Choose two)

Accepted Answer

Qualified next-hop with varying preference values. Option A (Qualified next-hop with varying preference values) is correct because Junos static routes support multiple qualified next-hops, each with its own preference; if the primary next-hop fails, the route with the next-lower preference becomes active, providing path redundancy. Option D (Recursive next-hop tracking via RPM or routing table lookups) is correct because a static route can resolve its next-hop recursively, and RPM (Real-time Performance Monitoring) probes or routing-table lookups can detect when the resolved next-hop becomes unreachable, allowing the route to be withdrawn or replaced. Option B (IGMP snooping) is a Layer 2 multicast optimization and does not provide static-route path redundancy. Option C (OSPF area stubbing) is a dynamic routing design technique for reducing LSAs, not a static-route feature. Option E (BGP AS-path prepending) is a BGP path-manipulation tool and cannot be applied to plain static routes.

Answer

IGMP snooping on static interfaces

Answer

OSPF area stubbing

Answer

BGP AS-path prepending on static routes

Question 2

Which operational command displays the configured member IDs, priorities, and roles in an EX Series Virtual Chassis?

Accepted Answer

show virtual-chassis. The 'show virtual-chassis' command displays member IDs, roles, priorities, and serial numbers.

Answer

show lacp aggregated-devices

Answer

show chassis alarms

Answer

show vrrp mastership

Question 3

Which command allows you to inspect the active forwarding table entries and verify next-hops on a Junos router?

Accepted Answer

show route forwarding-table. 'show route forwarding-table' displays the active forwarding table entries that the Packet Forwarding Engine (PFE) actually uses to forward packets, including next-hop information. This is the command that verifies what the router is really doing at the forwarding plane, not just what the routing protocol advertised.

Answer

show interfaces extensive

Answer

show pfe traffic

Answer

show routing-engine status

Question 4

Which TWO traffic conditions will trigger storm control drops on a configured switch interface? (Choose two)

Accepted Answer

Multicast traffic rate exceeding the configured threshold. Storm control on a switch interface monitors Layer 2 traffic rates and drops frames when a configured threshold is exceeded, and it applies to broadcast, multicast, and unknown unicast traffic. Option A is correct because multicast traffic exceeding the configured threshold is one of the traffic types storm control polices, so it triggers drops. Option D is correct because broadcast traffic exceeding the configured threshold is the classic storm control trigger, suppressing broadcast storms on the interface. Option B is wrong because unicast destined for known active MAC addresses is normal, expected forwarding traffic and is not counted by storm control (only unknown unicast is). Option C is wrong because CPU control plane queue utilization is a control-plane policing concern, not an interface storm control action. Option E is wrong because BPDUs are control frames handled by Spanning Tree, not storm-control-monitored data traffic.

Answer

Unicast traffic destined for known active MAC addresses exceeding average utilization

Answer

CPU control plane queue utilization exceeding 90%

Answer

BPDU control frames exceeding Spanning Tree hello timers

Question 5

You need to configure MACsec on an EX4300 switch interface. Which cipher suite is configured by default when MACsec is enabled without specifying an explicit cipher suite?

Accepted Answer

GCM-AES-128. When MACsec is enabled in Junos without specifying a cipher suite, GCM-AES-128 is used by default.

Answer

AES-CBC-128

Answer

SHA-256-HMAC

Answer

GCM-AES-256

Question 6

Which Junos command displays detailed information about OSPF neighbor states, including dead timer countdowns and address bindings?

Accepted Answer

show ospf neighbor detail. The command 'show ospf neighbor detail' displays comprehensive information about each OSPF neighbor, including neighbor state (Full, 2-Way, etc.), neighbor ID, interface address, dead timer countdown, and area. This is the go-to command for verifying adjacency health and troubleshooting OSPF neighbor issues on Junos devices.

Answer

show ospf statistics

Answer

show route table inet.0

Answer

show ospf database detail

Question 7

During the establishment of an OSPF adjacency, two routers exchange Database Description (DBD) packets. What is the primary purpose of the DBD packet exchange in the OSPF protocol sequence?

Accepted Answer

To synchronize link-state database summaries between neighbors. The DBD (Database Description) packet exchange is the second stage of OSPF adjacency formation, after Hello packets establish bidirectional communication. Its purpose is to exchange summary headers of each router's link-state database so both routers can determine which LSAs they are missing and need to request via Link-State Request packets. This synchronization ensures both neighbors have an identical view of the topology before entering the Full state.

Answer

To discover directly connected neighbors on a shared segment

Answer

To request specific missing LSAs from a neighbor's database

Answer

To explicitly acknowledge the receipt of specific LSA updates

Question 8

You are configuring a GRE tunnel carrying IPv6 traffic over an IPv4 transport network (GRE over IPv4). Which interface family must be configured under the gr- interface unit?

Accepted Answer

family inet6. The GRE tunnel is being used to carry IPv6 traffic, so the logical unit must be configured with family inet6 to process IPv6 packets. The transport is IPv4, but that is handled by the tunnel's source/destination addresses configured under the tunnel parameters, not by the unit's family. Configuring family inet6 on the gr- interface unit enables IPv6 forwarding, addressing, and protocol processing inside the tunnel.

Answer

family inet

Answer

family iso

Answer

family mpls

Question 9

What is the default bridge priority value assigned to Juniper EX Series switches when RSTP is enabled?

Accepted Answer

32768. Juniper EX Series switches use the IEEE 802.1D/802.1w default bridge priority of 32768 when RSTP is enabled. Bridge priority is a 16-bit value expressed in increments of 4096, and 32768 is the midpoint of the range, making it the standard default across vendors. The bridge with the lowest priority (and then lowest MAC) becomes root.

Answer

61440

Answer

0

Answer

4096

Question 10

What is the primary benefit of enabling edge port configuration on switch access ports connected to end devices?

Accepted Answer

It allows the port to transition immediately to the forwarding state, avoiding startup delays.. Enabling edge port configuration on switch access ports connected to end devices allows the port to transition immediately to the forwarding state, bypassing the listening and learning states of STP/RSTP. This avoids startup delays (up to 30 seconds with classic STP) and improves convergence for end-user devices. Edge ports are also known as PortFast in Cisco terminology.

Answer

It forces the port to operate exclusively in full-duplex mode.

Answer

It increases the interface bandwidth by disabling spanning tree calculations entirely.

Answer

It enables automatic detection of unauthorized rogue bridges on access links.