JN0-106 Routing Fundamentals Practice Test 6 — 15 Questions

Question 1

A network engineer configures a static route to 10.0.0.0/8 with a preference of 20. An OSPF internal route to 10.0.0.0/8 has a default preference of 10. Which route will be active in the routing table?

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

Accepted Answer

The OSPF route, because of lower preference.. In Junos, the active route in the routing table is determined by the lowest preference value. OSPF internal routes have a default preference of 10, while static routes have a default preference of 5, but here the static route is configured with a preference of 20. Since OSPF's preference (10) is lower than the static route's preference (20), the OSPF route is chosen as active.

Answer

Both routes, because they have different protocols.

Answer

Neither, because of a conflict.

Answer

The static route, because it is manually configured.

Question 2

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 3

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 4

An engineer is configuring multiple static routes to the same destination for redundancy. The primary link uses 192.168.1.1 and the backup uses 192.168.2.1. They want the backup to be used only when the primary next-hop is unreachable. Which configuration is correct?

Accepted Answer

Configure the primary with a lower preference and the backup with a higher preference.. In JUNOS, a lower preference value indicates a more preferred route. By setting the primary next-hop (192.168.1.1) with a lower preference (e.g., 5) and the backup next-hop (192.168.2.1) with a higher preference (e.g., 10), the primary route is installed in the routing table. If the primary next-hop becomes unreachable, the route is withdrawn, and the backup route with the higher preference is then installed, providing redundancy.

Answer

Configure the primary with a higher preference and the backup with a lower preference.

Answer

Configure two static routes with equal preferences; the active route will be chosen based on next-hop IP.

Answer

Configure the routes with the same preference but use a policy to set metric.

Question 5

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 6

Which TWO configuration statements are valid for defining a static route on a Junos device?

Accepted Answer

set routing-options static route 10.0.0.0/8 discard. Option A is correct because Junos supports the discard next-hop on a static route, which silently drops matching traffic and is configured exactly as set routing-options static route 10.0.0.0/8 discard. Option C is correct because qualified-next-hop is a valid Junos static-route next-hop type that allows a per-next-hop preference, so set routing-options static route 10.0.0.0/8 qualified-next-hop 192.168.1.1 preference 10 is syntactically valid. Option B is wrong because reject-all is not a valid Junos static-route next-hop keyword; the valid reject form is simply reject. Option D is wrong because Junos static routes do not use a metric statement; route preference is set with preference, not metric. Option E is wrong because passive is not a valid static-route option in Junos.

Answer

set routing-options static route 10.0.0.0/8 reject-all

Answer

set routing-options static route 10.0.0.0/8 next-hop 192.168.1.1 metric 10

Answer

set routing-options static route 10.0.0.0/8 passive

Question 7

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 8

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.

Answer

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

Answer

The route becomes hidden.

Question 9

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.

Question 10

An administrator configures a static route to 192.168.2.0/24 with next-hop 10.0.0.1. The route does not appear in the routing table. What is the most likely cause?

Accepted Answer

The next-hop 10.0.0.1 is not reachable.. A static route will only be installed in the routing table if the next-hop address is reachable via an active route in the routing table. If 10.0.0.1 is not reachable (e.g., no route to that subnet, or the interface is down), Junos will reject the static route and not place it in the inet.0 table. This is a fundamental validation check in Junos that prevents black-hole routing.

Answer

The static route has a higher preference than an existing dynamic route.

Answer

The configuration was not committed.

Answer

The prefix 192.168.2.0/24 already exists in the forwarding table.

Question 11

A router has an OSPF route to 10.10.10.0/24 with preference 10 and a static route to the same prefix with preference 5. Which route is active in the routing table?

Accepted Answer

The static route. In Junos, the active route in the routing table is determined by the route preference (administrative distance). A lower preference value indicates a more trusted route. Here, the static route has a preference of 5, which is lower than the OSPF route's preference of 10, so the static route is preferred and becomes active.

Answer

The OSPF route

Answer

Neither route

Answer

Both routes

Question 12

An engineer configures two static routes to 172.16.0.0/16 with next-hops 10.0.1.1 and 10.0.2.1, both with the same preference and same metric. How does Junos handle traffic to this prefix?

Accepted Answer

It load balances via ECMP.. Junos uses Equal-Cost Multipath (ECMP) when multiple static routes to the same destination prefix have identical preference (administrative distance) and metric. Since both routes to 172.16.0.0/16 have the same preference (default 5 for static routes) and metric (0 by default), Junos installs both in the forwarding table and load-balances traffic across the two next-hops (10.0.1.1 and 10.0.2.1) per-flow or per-packet depending on the configured hash algorithm.

Answer

It uses active/passive selection.

Answer

It uses only the first configured route.

Answer

It drops traffic due to ambiguity.

Question 13

An administrator executes 'show route 192.168.1.0/24' and sees no output, but the route is configured. Which command should be used to display the reason the route is not active?

Accepted Answer

show route hidden. The 'show route hidden' command displays routes that are present in the routing table but are not active due to reasons such as a next-hop being unreachable, a routing policy rejecting the route, or a route preference conflict. When a route is configured but not shown in the standard 'show route' output, it is likely hidden, and this command reveals the specific reason (e.g., 'next-hop unreachable' or 'rejected by policy').

Answer

show log messages

Answer

show route protocol static

Answer

show route forwarding-table

Question 14

You configure an aggregate route for 172.16.0.0/16. What must exist for this aggregate to be active in the routing table?

Accepted Answer

A contributing route (more specific route within the aggregate range). The correct option is C: a contributing route (a more specific route within the aggregate range) must exist for the aggregate to become active. In Junos, an aggregate route is only installed into the routing table when at least one more-specific route covered by the aggregate prefix is present in the routing table; for 172.16.0.0/16, that means a route such as 172.16.1.0/24 must be learned or configured. Option A is incorrect because a directly connected interface on the exact aggregate subnet is not required, and a more-specific connected route would itself serve as the contributing route. Option B is incorrect because a static route to the aggregate prefix does not activate the aggregate and would conflict with the aggregate's purpose. Option D is incorrect because aggregate routes are not unconditionally active; they depend on the presence of contributing routes.

Answer

A directly connected interface on that subnet

Answer

A static route to the aggregate prefix

Answer

Nothing; the aggregate is always active once committed.

Question 15

A static route to 10.0.0.0/8 has next-hop 192.168.1.1. The route is not installed in the routing table. Which condition must be met for the route to become active?

Accepted Answer

The next-hop 192.168.1.1 must be reachable via an active route (e.g., a direct or OSPF route).. For a static route to be installed in the Junos routing table, its next-hop must be reachable via an active route in the routing table. This is because Junos performs recursive next-hop resolution: it looks up the next-hop IP address (192.168.1.1) in the routing table and requires a valid, active route (e.g., a directly connected or OSPF-learned route) to that address. Without this, the static route remains hidden and is not installed.

Answer

The static route must have a lower preference than any dynamic route to the same prefix.

Answer

The next-hop must have an ARP entry in the ARP table.

Answer

The metric of the static route must be lower than that of any other route to the same prefix.