JN0-106 Routing Fundamentals Practice Test 6 — 15 Questions

Question 1

Refer to the exhibit. What does the 'user' type indicate about the route?

Accepted Answer

The route was manually configured.. In Junos, the 'user' type in a route table indicates that the route was manually configured, typically via a static route statement under the 'routing-options' hierarchy. This distinguishes it from routes learned dynamically through routing protocols or derived from the kernel's interface addresses.

Answer

The route is from the kernel.

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The route is a default route generated by the router.

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The route was learned from a routing protocol.

Question 2

An engineer configures a static route to 192.168.0.0/16 with next-hop 172.16.1.1. The static route appears as 'hidden' in the routing table. What is the most likely cause?

Accepted Answer

The next-hop address 172.16.1.1 is unreachable. In JUNOS, a static route with a next-hop that is not reachable (i.e., there is no active route to the next-hop) is automatically placed in a 'hidden' state. The most likely cause is that the next-hop 172.16.1.1 is unreachable.

Answer

The static route preference is set too high

Answer

The static route has not been committed

Answer

The static route is a discard route

Question 3

Two routers running IBGP with full mesh have a routing loop for prefix 10.1.1.0/24. Both routers have an IBGP route (preference 170) for the prefix with next-hop 10.2.2.2, and an OSPF route (preference 10) for the same prefix. The OSPF next-hop on each router points to the other router's loopback interface. Which action should be taken to stop the loop while preserving BGP route advertisement?

Accepted Answer

Increase the OSPF preference for 10.1.1.0/24 to 175. Increasing the OSPF preference for 10.1.1.0/24 to 175 makes the IBGP route (preference 170) more preferred than the OSPF route. This breaks the routing loop where each router's OSPF route points to the other's loopback, while preserving the IBGP route advertisement. The loop occurs because both routers prefer the OSPF route (preference 10) over IBGP (preference 170), causing traffic to bounce between them.

Answer

Add a static route for 10.1.1.0/24 with next-hop 10.2.2.2

Answer

Configure 'set protocol bgp group internal-mesh local-address 10.2.2.2' to set next-hop to self

Answer

Use route reflection to break the loop

Question 4

A route learned via BGP appears as 'hidden' in the routing table. Which condition is most likely the cause?

Accepted Answer

The BGP next-hop is unreachable. In JUNOS, a BGP route is marked as 'hidden' in the routing table when the next-hop address is not reachable via any active route in the inet.0 table. This is a fundamental BGP path selection prerequisite: the next-hop must be resolvable (typically via an IGP or static route) for the route to be considered active and installed.

Answer

The BGP route has a higher AS path length than another route

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The BGP route has been rejected by a policy

Answer

The BGP local preference is too high

Question 5

Refer to the exhibit. Why is the route for 192.168.1.0/24 hidden?

Accepted Answer

The next-hop is unreachable. A route is hidden in the JUNOS routing table when its next-hop is unreachable. The show route command displays only active routes; if the next-hop address is not reachable via any active interface or route, the route is suppressed (hidden) and not used for forwarding. This is a fundamental behavior of JUNOS route selection and differs from Cisco IOS, which may still display such routes.

Answer

The route has a higher metric

Answer

The route has a lower preference

Answer

The route is not committed

Question 6

Refer to the exhibit. The route for 192.168.0.0/16 is hidden. What is the most likely reason?

Accepted Answer

The BGP next-hop is unreachable. In JUNOS, a BGP route is hidden when the next-hop address is not reachable via any active route in the routing table. The router cannot install the route into the forwarding table because it lacks a valid path to the next-hop, causing the route to be marked as hidden. This is a common issue when the next-hop is not covered by a directly connected or static route, or when the IGP route to the next-hop is missing.

Answer

The route has a lower local preference

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The route has a longer AS path

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The route has a higher MED value

Question 7

A network engineer configures a static route to a remote network. They want the route to be automatically removed from the routing table if the directly connected interface used to reach the next hop fails. Which configuration approach should be used?

Accepted Answer

Configure the next-hop as the interface name.. Configuring the next-hop as an interface name (e.g., ge-0/0/0) creates a static route that is automatically removed from the routing table when that interface goes down. This is due to the route being 'qualified' by the interface's operational state; if the interface fails, the route is withdrawn. In contrast, using an IP address as the next-hop does not tie the route to the interface's state, so the route remains even if the interface fails, as long as the next-hop is reachable via another path.

Answer

Configure a higher metric on the static route.

Answer

Configure a preference of 0 on the static route.

Answer

Configure the next-hop as an IP address.

Question 8

A network administrator is troubleshooting a missing route in the routing table. The route is learned via OSPF, and the OSPF neighbor adjacency is up. Which command would help determine if OSPF received the route?

Accepted Answer

show ospf database. The OSPF link-state database (LSDB) contains all received LSAs, including Type 1 (Router) and Type 3 (Summary) LSAs that advertise routes. Even if a route is not installed in the routing table (e.g., due to a higher administrative distance or a missing route preference), the 'show ospf database' command confirms whether OSPF has received the LSA carrying that route. This directly answers the question of whether OSPF received the route, independent of route installation.

Answer

show route protocol ospf

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show ospf neighbor

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show interface terse

Question 9

A network is experiencing intermittent routing loops. The engineer discovers that routes are being redistributed from OSPF into BGP and then from BGP back into OSPF on different routers. What is the most effective way to prevent this?

Accepted Answer

Configure route filters to prevent mutual redistribution.. Mutual redistribution between OSPF and BGP creates routing loops when routes are exported from OSPF into BGP on one router and then re-injected back into OSPF on another router. The most effective way to prevent this is to use route filters (e.g., prefix lists, route-maps, or policy-statement in Junos) to control which routes are redistributed, ensuring that routes learned from one protocol are not re-advertised back into the same protocol. This breaks the redistribution cycle without altering protocol preference or metrics.

Answer

Use a higher preference for BGP routes.

Answer

Set a lower metric on OSPF routes.

Answer

Increase the OSPF cost on interfaces.

Question 10

A static route is configured with next-hop 10.0.0.1, but the route does not appear in the routing table. The interface ge-0/0/0 has IP 192.168.1.2/24 and is up. What is the most likely reason?

Accepted Answer

The next-hop IP is not on a directly connected subnet.. D is correct because Junos requires the next-hop IP of a static route to be reachable via a directly connected subnet for the route to be installed in the routing table. Since the next-hop 10.0.0.1 is not on the same subnet as the interface ge-0/0/0 (192.168.1.2/24), the route remains hidden and does not appear in the routing table.

Answer

The static route has a preference of 5.

Answer

The route is hidden due to an import policy.

Answer

The static route is configured with the 'discard' option.

Question 11

A network must forward traffic to 10.1.1.0/24 through a specific next-hop 192.168.1.1, even if a dynamic route with a lower preference is available. Which configuration will achieve this?

Accepted Answer

Configure a static route to 10.1.1.0/24 with next-hop 192.168.1.1 and preference 5.. A static route can be configured with a preference value lower than any dynamic routing protocol's default preference. In Junos, the default preference for OSPF internal routes is 10, for IS-IS level 1 is 15, for RIP is 100, and for BGP is 170. By setting the static route to 10.1.1.0/24 with next-hop 192.168.1.1 and preference 5, it will have a lower preference value than these defaults. Therefore, even if a dynamic route with a lower preference (i.e., a smaller number but still greater than 5) exists, the static route will be installed in the routing table and used for forwarding, satisfying the requirement to always forward traffic through the specified next-hop.

Answer

Configure the dynamic protocol to export the route with a metric of 1.

Answer

Configure a filter to reject the dynamic route.

Answer

Configure a static route to 10.1.1.0/24 with next-hop 192.168.1.1 and preference 15.

Question 12

Which TWO statements about route preferences in Junos are correct?

Accepted Answer

Direct routes have a default preference of 0.. In Junos, direct (connected) routes have a default route preference of 0, which is the highest possible preference, ensuring they are always preferred over other route types for directly attached networks. Option C is correct because OSPF internal routes (both intra-area and inter-area) have a default preference of 10 in Junos, which is lower than most other dynamic routing protocols, making OSPF routes more preferred by default.

Answer

The preference of a route cannot be changed.

Answer

Static routes have a default preference of 10.

Answer

BGP routes have a default preference of 200.

Question 13

Refer to the exhibit. How many next hops are installed for the 10.1.1.0/24 route?

Accepted Answer

2. The route 10.1.1.0/24 has two next hops installed because the routing table shows two distinct next-hop addresses (e.g., 192.168.1.1 and 192.168.2.1) under the same route entry. In JUNOS, when equal-cost paths exist, the route is installed with multiple next hops, and the count reflects the number of unique next-hop entries, not the number of interfaces or paths in a load-balancing set.

Answer

4

Answer

3

Answer

1

Question 14

Refer to the exhibit. If the primary next-hop (192.168.1.1) becomes unreachable, what will happen to the route?

Accepted Answer

The secondary next-hop (192.168.2.1) will be used.. In Junos, when a route has multiple next-hops configured (e.g., primary and secondary), the secondary next-hop serves as a backup. If the primary next-hop (192.168.1.1) becomes unreachable, Junos automatically fails over to the secondary next-hop (192.168.2.1) without removing the route from the routing table. This behavior is controlled by the 'next-hop' configuration under a static route or via routing protocol policies, ensuring continuous reachability.

Answer

The route is removed from the routing table.

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The route remains but with the primary next-hop marked as unreachable.

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The route becomes hidden.

Question 15

Refer to the exhibit. What is the most likely cause of this BGP route being hidden?

Accepted Answer

The next-hop 192.168.100.1 is not reachable via any active route.. In JUNOS, a BGP route is hidden when the next-hop address is not reachable via any active route in the routing table. The show route protocol bgp command displays the route as hidden if the next-hop 192.168.100.1 is not resolvable, because BGP requires a valid IGP or static route to the next-hop for the route to be considered active and installed in the forwarding table.

Answer

The route has a higher preference than another route.

Answer

The BGP session to 10.0.0.2 is down.

Answer

The prefix 10.1.1.0/24 is filtered by an import policy.