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

Question 1

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

Accepted Answer

show route instance engineering. The command 'show route instance engineering' is the correct way to verify interface bindings for a routing instance on Junos devices. It displays the routing table for the specified instance, including the interfaces that are bound to it. This command is part of the operational mode and directly shows the association between interfaces and the routing instance.

Answer

show interfaces instance engineering

Answer

show configuration routing-instances engineering

Answer

show forwarding-table instance engineering

Question 2

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 (inet.0) instance (option C) is the master routing instance in Junos OS and fully supports running dynamic interior routing protocols such as OSPF and IS-IS in its inet.0 routing table, making it a valid answer. A virtual-router routing instance (option A) creates its own independent routing tables (e.g., inet.0) and protocol processes, so OSPF and IS-IS can be configured and run within it just as in the master instance, which is why it is also correct. The no-structural-instance option (B) is not a valid Junos routing instance type. The forwarding instance (D) is used only to separate forwarding tables for filter-based forwarding and does not run routing protocols. The l2vpn instance (E) is a Layer 2 VPN routing instance that operates at Layer 2 and does not support interior IP routing protocols like OSPF or IS-IS.

Answer

no-structural-instance

Answer

forwarding

Answer

l2vpn

Question 3

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All contributing routes have been suppressed or withdrawn.. Option A is correct because an aggregate route is only installed/active when it has contributing routes; if all contributors are suppressed or withdrawn, the aggregate has no components and remains inactive. Option B is correct because without any more-specific contributing routes present in the routing table, the aggregate route has nothing to summarize and will not become active. Option D is correct because explicitly deactivating the aggregate in the configuration (for example, with a deactivate statement) removes it from consideration, so it cannot be installed in the routing table. Option C is not correct because BGP split-horizon is an advertisement rule that prevents sending routes back out the same interface/session, not a condition that keeps an aggregate route inactive in the local routing table. Option E is not correct because high CPU utilization can slow processing but is not a defined condition that causes an aggregate route to remain inactive.

Answer

BGP split-horizon rule is preventing advertisement.

Answer

The router's CPU utilization exceeds 90%.

Question 4

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.. Option C is correct because a static route configured with the 'reject' parameter causes the router to actively respond to matching packets by sending an ICMP destination unreachable message back to the source, rather than forwarding them. Option D is correct because the reject route is still a valid, active route that gets installed into the forwarding table (RIB/FIB), where it is used to trigger the rejection behavior for matching traffic. Option A is wrong because silent dropping describes a 'blackhole' route, not a 'reject' route, which explicitly notifies the sender. Option B is wrong because reject routes do not forward matching packets to the default gateway. Option E is wrong because MPLS label imposition is unrelated to static reject route processing.

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 5

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. Option C, 'show route table inet.0 static', is correct because it filters the inet.0 routing table to display only static routes, letting you inspect their prefixes, next hops, and preference values. Option D, 'show route protocol static', is correct because it filters the routing table by the protocol that installed the routes, showing all static routes regardless of table, which verifies their presence and status. Option A, 'show forwarding-table static', is not a valid Junos command for inspecting static routes in the routing table. Option B, 'show static-routes active', is not a valid Junos command syntax. Option E, 'show interfaces static', is invalid because 'static' is not a valid interface filter and interfaces do not represent static routes.

Answer

show forwarding-table static

Answer

show static-routes active

Answer

show interfaces static

Question 6

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

Accepted Answer

Aggregate routes have a default preference of 130.. Option B is correct because in Junos OS aggregate routes are assigned a default preference of 130, which is higher (less preferred) than static routes (5) and OSPF (10) but lower than BGP (170). Option E is correct because the primary purpose of an aggregate route is to summarize multiple contributing static or dynamic routes into a single, more specific advertisement, reducing routing table size and improving stability. Option A is incorrect because it duplicates the same claim as B but is not marked correct, and only one statement about the default preference of 130 is valid. Option C is incorrect because an aggregate route is only active (installed in the forwarding table) when at least one contributing route exists; without contributors, it remains inactive and does not forward traffic. Option D is incorrect because aggregate routes use a discard next-hop by default and do not require a physical interface to be specified as the next-hop.

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.

Question 7

An administrator is configuring route leaking between a virtual-router routing instance and the default inet.0 table. Which THREE methods or configuration constructs can be used to achieve route leaking in Junos? (Choose three)

Accepted Answer

Using logical tunnel (lt) or physical patch cables between instance interfaces.. Route leaking in Junos between a virtual-router instance and inet.0 can be accomplished by interconnecting instance interfaces with logical tunnel (lt) interfaces or physical patch cables, which physically or virtually pass traffic and let routes be learned across the two routing instances (B). Another supported method is configuring rib-groups under routing-options, which copies or imports routes from one routing table into another, such as from a virtual-router table into inet.0 (D). Import and export policies between routing instances also enable route leaking by matching and accepting routes from one instance's table into another, for example with vrf-import/vrf-export or instance import/export policies (E). Option A is incorrect because an aggregate route with a discard next-hop only creates a summary route locally and does not leak routes between routing tables. Option C is incorrect because BGP auto-discovery alone, without policies or explicit peering/route-target configuration, does not automatically leak routes across all virtual routers.

Answer

Configuring an aggregate route with a discard next-hop in inet.0.

Answer

Enabling BGP auto-discovery across all virtual routers without policies.

Question 8

When configuring advanced load balancing under forwarding-options, which THREE hash-key options are available to administrators in Junos OS? (Choose three)

Accepted Answer

layer-4. The three correct answers are C. layer-4, D. layer-3, and E. layer-2, because Junos OS under the [edit forwarding-options] hierarchy supports the hash-key statement with the layer-2, layer-3, and layer-4 options to control which packet header fields are used for per-flow load balancing. The layer-2 option hashes on Layer 2 header fields such as source and destination MAC addresses, the layer-3 option hashes on Layer 3 header fields such as source and destination IP addresses, and the layer-4 option hashes on Layer 4 header fields such as source and destination TCP/UDP ports. These three options are the standard granularity choices administrators can combine or select individually when tuning load-balancing behavior for services such as aggregated Ethernet or per-packet forwarding. Option A. mpls-label is not one of the hash-key options exposed in this context, and option B. payload-checksum is not a valid hash-key selection either, since Junos does not offer a payload-checksum-based hash key under forwarding-options.

Answer

mpls-label

Answer

payload-checksum

Question 9

An administrator is configuring load balancing across multiple equal-cost paths on an MX Series router. Which statement is correct regarding Junos default load-balancing behavior?

Accepted Answer

You must configure a routing policy with the 'load-balance' action and apply it to 'export' under 'routing-options'.. In Junos, per-flow load balancing across multiple equal-cost paths is not enabled by default for all protocols. To activate it, you must configure a routing policy that includes the `load-balance per-packet` action and apply it as an export policy under `[routing-options]`. This policy is then evaluated for routes installed in the forwarding table, causing the router to install all equal-cost next-hops and hash flows across them. Without this policy, only one next-hop is selected and used, even if multiple equal-cost paths exist.

Answer

Load balancing requires enabling BGP multipath globally under the system hierarchy.

Answer

Junos automatically load-balances traffic per packet across all equal-cost paths by default without policy configuration.

Answer

Load balancing is configured directly within the firewall filter configuration using the 'sample' action.

Question 10

When configuring load balancing on a Juniper Networks router, which TWO actions or components are necessary to achieve functional per-flow load balancing across multiple paths? (Choose two)

Accepted Answer

A routing policy containing the 'load-balance' action statement.. Option A is correct because per-flow load balancing on Juniper routers is enabled by including the 'load-balance' action (e.g., 'then load-balance per-packet' or 'per-flow') inside a routing policy, which instructs the forwarding table to distribute traffic across multiple equal-cost next hops. Option B is correct because that policy must actually be applied to the forwarding table via 'set routing-options forwarding-table export <policy-name>'; without this export statement the load-balance action has no effect on the installed forwarding entries. Option C is incorrect because a 'forwarding' routing-instance type is used for filter-based forwarding/VPN scenarios, not for enabling ECMP load balancing. Option D is incorrect because MPLS encapsulation is unrelated to per-flow load balancing and is not required for IP ECMP. Option E is incorrect because firewall filters on BGP interfaces are used for traffic filtering or marking, not for enabling load balancing across paths.

Answer

Setting the routing-instance type to 'forwarding'.

Answer

Enabling MPLS encapsulation on all core interfaces.

Answer

A firewall filter applied to every interface running BGP.

Question 11

Which THREE characteristics are true regarding Junos aggregate routes? (Choose three)

Accepted Answer

They require at least one active, more-specific contributing route to become active.. Option B is correct because a Junos aggregate route is only installed into the routing table when at least one more-specific contributing route is active, which is the fundamental condition for the aggregate to become active. Option C is correct because aggregate routes can be formed from contributing routes learned via any routing protocol (such as OSPF, IS-IS, or BGP) or from static routes, giving administrators flexibility in summarizing reachability. Option D is correct because Junos assigns aggregate routes a default route preference of 130, which is higher (less preferred) than static routes (5) and OSPF internal routes (10), but lower than BGP (170). Option A is incorrect because aggregate routes do not automatically install a discard next-hop when no contributing routes exist; they simply remain inactive unless configured with a discard or reject next-hop manually. Option E is incorrect because aggregate route prefix length is explicitly configured by the administrator and is not dynamically derived from any physical interface subnet mask.

Answer

They automatically drop matching traffic by installing a discard next-hop when no contributing routes exist.

Answer

They dynamically adjust their prefix length based on the subnet mask of the primary physical interface.

Question 12

When configuring a static route in Junos, which THREE next-hop options are valid and supported? (Choose three)

Accepted Answer

discard. Option A, discard, is a valid Junos static-route next-hop that silently drops matching traffic without sending ICMP messages, commonly used to create blackhole routes. Option B, reject, is also valid and causes the router to drop the packet while returning an ICMP unreachable message to the source. Option C, next-hop <IP-address>, is the standard valid next-hop specifying the directly reachable IP address of the adjacent device for forwarding traffic. Options D and E are not next-hop types: metric-out is a route preference/attribute parameter used in routing policy to influence metric values, and forwarding-class is a class-of-service attribute assigned to traffic, not a next-hop specification.

Answer

metric-out

Answer

forwarding-class

Question 13

A network engineer is configuring a static route on a Junos device and wants to ensure that the route remains installed in the routing table only when a specific downstream condition is met. The engineer decides to use a qualified next hop with a condition. Which configuration correctly associates a condition with a qualified next hop?

Accepted Answer

set routing-options static route 10.0.0.0/24 condition my-condition qualified-next-hop 192.168.1.1. The correct configuration places the condition statement before the qualified next hop in the static route hierarchy. This allows the route to be installed only when the specified condition is met, such as a route to a destination being present. The condition is defined separately under routing-options conditions.

Answer

set routing-options static route 10.0.0.0/24 next-hop 192.168.1.1 condition my-condition

Answer

set routing-options static route 10.0.0.0/24 qualified-next-hop 192.168.1.1 condition my-condition preference 10

Answer

set routing-options static route 10.0.0.0/24 qualified-next-hop 192.168.1.1 condition my-condition

Question 14

An administrator has configured a forwarding-type routing instance to perform filter-based forwarding. Which configuration statement is mandatory under the routing-instances hierarchy to properly define this instance type?

Accepted Answer

set routing-instances dept-fwd instance-type forwarding. Filter-based forwarding (FBF) on Junos requires a routing instance of type 'forwarding'. This instance type creates a Virtual Routing and Forwarding (VRF) table that is populated only by firewall filter 'then routing-instance' actions, not by a routing protocol. The mandatory statement is therefore 'set routing-instances <name> instance-type forwarding'.

Answer

set routing-instances dept-fwd routing-options interface ge-0/0/0.0

Answer

set routing-instances dept-fwd instance-type virtual-router

Answer

set routing-instances dept-fwd instance-type l3vpn

Question 15

By default, what is the Junos routing protocol preference value assigned to static routes?

Accepted Answer

5. In Junos OS, the default routing protocol preference (also called administrative distance) for static routes is 5. This low value makes static routes highly preferred over routes learned from dynamic protocols like OSPF (preference 10) or BGP (preference 170). The preference value is used to select the active route when multiple routes to the same destination exist from different sources.

Answer

170

Answer

10

Answer

150