JNCIS-ENT Protocol Independent Routing Practice Test 2 — 15 Questions

Question 1

You are configuring a qualified next-hop for a static route in Junos to provide redundancy. Which parameter allows you to specify a secondary next-hop with a different preference value?

Accepted Answer

qualified-next-hop. Qualified next-hops allow administrators to assign specific preferences or metrics to individual next-hops of a static route.

Answer

alternate-path

Answer

secondary-route

Answer

backup-next-hop

Question 2

An engineer configures a static route pointing to an interface rather than an IP address. What potential issue can occur with interface-based static routes on multi-access Ethernet networks in Junos OS?

Accepted Answer

The router will generate an ARP request for every destination IP, potentially exhausting ARP cache.. On multi-access networks (like Ethernet), pointing a static route directly to an interface causes the router to ARP for every destination IP address it receives, potentially exhausting ARP tables (Proxy ARP behavior or ARP storm).

Answer

The packet forwarding engine will crash due to unresolvable MAC addresses.

Answer

The static route will immediately enter a hidden state due to missing next-hop IP.

Answer

BGP will automatically re-advertise the interface route into external ASNs.

Question 3

You configure an aggregate route and want to control which specific attributes or policies are applied when the aggregate is advertised by BGP. Which routing option is used to assign a specific contributing route tag or policy to an aggregate route?

Accepted Answer

set routing-options aggregate route 10.10.0.0/16 metric 100. Aggregate routes can have specific attributes like preference, metric, and tags assigned using the routing-options aggregate hierarchy.

Answer

set routing-instances aggregate-property

Answer

set protocols bgp aggregate-attribute 10.10.0.0/16

Answer

set routing-options aggregate route 10.10.0.0/16 policy

Question 4

Which command is used to display all configured static routes along with their active/inactive status in Junos?

Accepted Answer

show route protocol static. The show route protocol static command displays routes learned or defined via the static routing protocol.

Answer

show static routes summary

Answer

show configuration routing-options static

Answer

show route table inet.0 static

Question 5

When configuring a routing instance of type 'virtual-router', what is required to allow communication between the virtual router instance and the default routing instance?

Accepted Answer

Configure leaking routes between instances using rib-groups or routing policies.. Routing instances are isolated. To share routes between a virtual-router and the default instance, you must explicitly configure route leakage using export and import policies under routing-instances.

Answer

Connect a physical cable between two ports on the router (cable-patch).

Answer

Configure static routes with identical preferences in both instances.

Answer

Disable firewall filters on all loopback interfaces.

Question 6

You need to verify that load balancing is functioning properly across your core interfaces and wish to see the specific hash buckets assigned in the forwarding table. Which command should you execute?

Accepted Answer

show route forwarding-table destination 192.168.1.1. The show route forwarding-table destination command displays the next-hops and whether multiple equal-cost paths (load balancing) are active for a destination.

Answer

show system switchover status

Answer

show forwarding-options hash-results

Answer

show pfe statistics load-balance

Question 7

You want to ensure that a static route is only installed in the routing table when a specific tracked object or ping test succeeds. Which Junos feature should you pair with the static route?

Accepted Answer

RPM (Real-time Performance Monitoring) with static route tracking. RPM (Real-time Performance Monitoring) can be integrated with static routes to provide recursive tracking and dynamic route removal if ping probes fail (often called IP SLA equivalent in Junos).

Answer

OSPF sham-links

Answer

Keepalive timers on static routes

Answer

BFD synchronized static routes

Question 8

An administrator configures filter-based forwarding. The firewall filter uses the action 'then routing-instance custom-vr'. Where must the custom-vr routing instance be defined for the filter to accept this configuration without committing errors?

Accepted Answer

Under the [edit routing-instances] hierarchy.. Any routing instance referenced in a firewall filter action must be explicitly defined under the top-level 'routing-instances' hierarchy.

Answer

Under the [edit system FBF] hierarchy.

Answer

Under the [edit interfaces interface-name unit 0 family inet] hierarchy.

Answer

Under the [edit firewall family inet filter] hierarchy.

Question 9

You have configured load balancing across two uplinks using a routing policy. After committing the configuration, you notice that traffic is still exiting only via the primary link. What missing command under forwarding-options is necessary to activate the policy for forwarding table generation?

Accepted Answer

set routing-options forwarding-table export <policy-name>. To apply a load-balancing policy to the forwarding table, you must explicitly declare it under routing-options forwarding-table export.

Answer

set protocols load-balancing enable

Answer

set forwarding-options family inet load-balance

Answer

set interfaces load-balance-ecmp

Question 10

You need to ensure that traffic entering interface ge-0/0/1 is forced into a specific forwarding routing instance named 'corp-fwd', regardless of the destination IP address in the packet header. Which configuration steps must you perform?

Accepted Answer

Create a forwarding instance, write a firewall filter with 'then routing-instance corp-fwd', and apply the filter as input on ge-0/0/1.. Implementing FBF requires creating a forwarding instance, defining a firewall filter that matches the traffic and directs it to that instance, and applying the filter to the ingress interface.

Answer

Create a virtual-router instance and apply a static default route pointing to ge-0/0/1.

Answer

Configure a routing policy with 'then export corp-fwd' and apply it under protocols.

Answer

Enable proxy-ARP on ge-0/0/1 and assign the corp-fwd routing instance to the physical port.

Question 11

Which Junos routing instance type is best suited when you want to run MPLS L3VPNs on a Provider Edge (PE) router?

Accepted Answer

vrf. L3VPN routing instances are used on PE routers to maintain customer-specific VRF routing tables and exchange VPN-IPv4 routes via MP-BGP.

Answer

forwarding

Answer

virtual-router

Answer

no-structural-instance

Question 12

What is the default preference value for a direct route in Junos OS?

Accepted Answer

0. Direct routes (connected interfaces) have a preference value of 0 in Junos OS, making them the most trusted routes in the routing table.

Answer

5

Answer

20

Answer

10

Question 13

An administrator configures a static route with a next-hop that points to an indirect (recursive) address. What condition must be met for this static route to become active in the inet.0 routing table?

Accepted Answer

A more direct route to the next-hop IP must already exist and be active in inet.0.. A recursive static route requires a resolving active route in the routing table (usually learned via an IGP or BGP) that matches the next-hop IP address.

Answer

The static route preference must be set lower than 1.

Answer

The next-hop IP must be directly connected to a physical interface on the local router.

Answer

BGP multipath must be enabled under routing-options.

Question 14

An engineer configures multiple static routes to the same destination with different preference values. When all paths are up, how does Junos select which route is active in the routing table?

Accepted Answer

The route with the lowest preference value is installed as active.. Junos selects routes based primarily on preference (administrative distance). The route with the lowest preference value is installed as active. If preferences are equal, ECMP may occur depending on configuration.

Answer

The route configured last in the candidate configuration file becomes active.

Answer

The route with the highest metric value is preferred.

Answer

All routes are installed into the forwarding table for equal-cost multi-path load balancing.

Question 15

You are troubleshooting an aggregate route that is not being advertised to BGP peers. You verify that contributing routes are active in the routing table. What command should you use to check if the aggregate route itself is successfully generated and active in the local routing table?

Accepted Answer

show route protocol aggregate. The show route protocol aggregate command displays aggregate routes generated by the router and their active status.

Answer

show route summary aggregate

Answer

show bgp aggregate-routes

Answer

show routing-options aggregate detail