JNCIS-ENT Protocol Independent Routing Practice Test 3 — 15 Questions

Question 1

You want to configure load balancing across four distinct next-hops. By default, how many paths will Junos install into the forwarding table for ECMP if you configure a load-balancing policy without specifying path limits?

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

Accepted Answer

Up to 16 paths. By default, Junos supports up to 16 equal-cost paths (ECMP) for traffic forwarding, though this can be tuned.

Answer

Exactly 4 paths

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Up to 64 paths

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Only 1 path (no load balancing)

Question 2

Which statement best describes the behavior of a local route in Junos OS?

Accepted Answer

They represent IP addresses assigned directly to the router's local interfaces.. Local routes represent the IP addresses assigned directly to the router's interfaces (such as loopback or physical interface addresses).

Answer

They are static routes learned from neighbor routers via CDP.

Answer

They are manual loopback routes configured by network administrators.

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They are generated automatically whenever a BGP session drops.

Question 3

You need to isolate a set of interfaces into a separate routing table without running dynamic routing protocols inside that table. Which routing instance type should you deploy?

Accepted Answer

virtual-router. A forwarding instance or a virtual-router without protocols can work, but a virtual-router is typically used for routing table isolation, or a forwarding instance for pure FBF. To isolate interfaces with static routing only, a virtual-router instance is ideal.

Answer

l2vpn

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no-structural-instance

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nat

Question 4

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. Qualified next-hops and recursive next-hop tracking (or BFD/RPM integration) provide static route redundancy in Junos.

Answer

IGMP snooping on static interfaces

Answer

OSPF area stubbing

Answer

BGP AS-path prepending on static routes

Question 5

When configuring load balancing in Junos OS, which THREE header fields can be included in the hashing algorithm to compute the ECMP path? (Choose three)

Accepted Answer

Layer 4 TCP/UDP port numbers. Junos supports hash-key configuration options that include source IP, destination IP, and Layer 4 source/destination ports.

Answer

MAC address destination

Answer

VLAN ID tagging bits

Question 6

Which command verifies the interface bindings associated with a specific routing instance named 'engineering'?

Accepted Answer

show route instance engineering. The show route instance detail or show routing-instance command displays configuration details and interface bindings for specific instances.

Answer

show interfaces instance engineering

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show configuration routing-instances engineering

Answer

show forwarding-table instance engineering

Question 7

Which TWO routing instance types support running dynamic interior routing protocols like OSPF and IS-IS within Junos OS? (Choose two)

Accepted Answer

virtual-router. The default routing instance and the virtual-router routing instance both support running independent dynamic routing protocols.

Answer

no-structural-instance

Answer

forwarding

Answer

l2vpn

Question 8

An administrator is troubleshooting an aggregate route that is missing from the routing table. Which THREE conditions could cause an aggregate route to remain inactive? (Choose three)

Accepted Answer

All contributing routes have been suppressed or withdrawn.. Aggregate routes require active contributing routes, lack of suppression, and valid configuration under routing-options.

Answer

BGP split-horizon rule is preventing advertisement.

Answer

The router's CPU utilization exceeds 90%.

Question 9

Which TWO actions occur when a packet matches a static route configured with the 'reject' parameter? (Choose two)

Accepted Answer

An ICMP destination unreachable message is sent back to the packet source.. Reject installs the route into the forwarding table and ensures packets matching it generate an ICMP unreachable message while being dropped.

Answer

The packet is silently dropped without any notification.

Answer

The packet is forwarded to the default gateway.

Answer

The packet is tagged with an MPLS label.

Question 10

When configuring Filter-Based Forwarding (FBF), which THREE components are absolutely mandatory for successful operation? (Choose three)

Accepted Answer

A firewall filter with 'then routing-instance <name>' action.. FBF requires a forwarding instance, a firewall filter with a routing-instance action, and the application of that filter to an interface input.

Answer

BGP multipath enabled across all core interfaces.

Answer

An RSVP-TE LSP tunnel configured between the routers.

Question 11

Which TWO commands can be used to inspect static routes or verify their status in Junos OS? (Choose two)

Accepted Answer

show route table inet.0 static. The show route protocol static and show route table inet.0 static commands are standard ways to inspect static routes.

Answer

show forwarding-table static

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show static-routes active

Answer

show interfaces static

Question 12

An administrator wants to configure load balancing across multiple static routes. Which THREE configuration elements are required to successfully implement ECMP load balancing for static routes in Junos? (Choose three)

Accepted Answer

Export of the load-balancing policy under 'routing-options forwarding-table export'.. ECMP load balancing requires multiple routes with equal preference/metric, a routing policy with 'then load-balance', and export of that policy to the forwarding table.

Answer

BFD enabled on all static route next-hops.

Answer

A virtual-router routing instance wrapper.

Question 13

When configuring a routing instance of type 'virtual-router', which THREE characteristics apply? (Choose three)

Accepted Answer

Interfaces can be assigned directly to the virtual-router instance.. Virtual routers have independent routing tables, support dynamic routing protocols, and operate separately from inet.0.

Answer

It requires MPLS label distribution protocols to function.

Answer

Route leaking between virtual-router and inet.0 is strictly prohibited by Junos architecture.

Question 14

Which TWO attributes distinguish direct routes from static routes in Junos OS? (Choose two)

Accepted Answer

Direct routes represent subnets attached to active local interfaces.. Direct routes have a preference of 0 and represent local interface subnets, whereas static routes have a default preference of 5 and are manually configured.

Answer

Static routes are created automatically when an interface comes up.

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Direct routes require manual IP address configuration under routing-options.

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Static routes cannot be used with recursive next-hops.

Question 15

Which TWO statements are true regarding aggregate routes in Junos OS? (Choose two)

Accepted Answer

Aggregate routes have a default preference of 130.. Aggregate routes summarize more-specific routes and do not forward traffic themselves unless paired with discard/reject or resolved via contributing routes.

Answer

Aggregate routes have a default preference of 130 in Junos.

Answer

An aggregate route automatically forwards traffic even if no contributing routes exist.

Answer

Aggregate routes require a physical interface to be specified as the next-hop.