JN0-106 Routing Fundamentals Practice Test 5 — 15 Questions

Question 1

Refer to the exhibit. A network administrator configured a static route to 10.0.0.0/24 with next-hop 192.168.1.1. The route is not appearing in the active routing table. What is the most likely reason?

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

Accepted Answer

The next-hop address is not reachable.. The exhibit shows that the route's next-hop type is 'Unreachable', indicating that the next-hop address 192.168.1.1 is not reachable. Since the next-hop is unreachable, the static route cannot be installed in the active routing table. Option B is incorrect because a reject route would show 'Reject' or 'Discard'. Option C is incorrect: even if an OSPF route existed with lower preference (higher priority), the static route would still appear as a backup; the problem here is next-hop unreachability. Option D is incorrect: a static route with preference 5 is low, meaning it is highly preferred; high preference would make it less preferred, but the route is not active due to unreachable next-hop, not preference.

Answer

The route is a reject route.

Answer

The route is being overridden by an OSPF route with lower preference.

Answer

The static route preference is too high.

Question 2

An organization has two ISPs and wants to load-balance traffic equally across both links for all outbound traffic. Which routing configuration approach should be used?

Accepted Answer

Configure two static default routes with equal metric values and enable ECMP.. Configuring two static default routes with equal metric values and enabling Equal-Cost Multi-Path (ECMP) allows the Juniper device to load-balance outbound traffic equally across both ISP links. ECMP uses per-flow or per-packet load balancing based on the hash of source/destination IP addresses and ports, ensuring traffic is distributed evenly without relying on dynamic routing protocols.

Answer

Configure two static default routes with different metric values.

Answer

Configure policy-based routing to match all traffic and forward to both ISPs.

Answer

Establish BGP sessions with both ISPs and rely on BGP path selection.

Question 3

You are the network engineer for a mid-sized enterprise with a Juniper MX router running Junos. The router has two uplinks to the internet: one to ISP-A via ge-0/0/0 (10.0.0.1/30) and one to ISP-B via ge-0/0/1 (10.0.0.5/30). You have configured static default routes to both ISPs: one to 10.0.0.2 and one to 10.0.0.6. Both routes have the same preference (default 5) and metric. You enabled ECMP to load-balance outbound traffic. After testing, you notice that all traffic is being sent only to ISP-A, and none to ISP-B. You verify that both interfaces are up and that the next-hop addresses are reachable. You check the routing table and see both routes are active but with different next-hop counts. What is the most likely cause of the traffic not being load-balanced?

Accepted Answer

One of the static routes resolves to multiple next hops, causing imbalance.. When both static default routes have the same preference and metric, Junos installs both in the routing table. However, ECMP load-balancing requires that each route resolve to a single next hop. If one static route resolves to multiple next hops (e.g., through a recursive lookup to a prefix with multiple paths), the route with a single next hop (ISP-A) becomes the sole active path for forwarding, while the multi-next-hop route (ISP-B) is not used for load balancing. This explains why all traffic goes to ISP-A despite both routes being present.

Answer

ECMP is not enabled in the forwarding-options.

Answer

The route to ISP-B is not active.

Answer

Hash-based load balancing requires per-packet configuration.

Question 4

Your Juniper router is running OSPF with multiple neighbors. You have a prefix 10.10.10.0/24 that is being learned via OSPF from two different routers: Router A with metric 30 and Router B with metric 20. The OSPF route from Router B is active. You want to ensure that traffic to 10.10.10.0/24 uses the path through Router A instead, even though it has a higher metric. You cannot change the OSPF metric on Router A. Which action should you take?

Accepted Answer

Use a routing policy to increase the preference of the OSPF route from Router B.. In JUNOS, route preference (administrative distance) determines which route is installed in the routing table when multiple protocols or sources provide the same prefix. By default, OSPF internal routes have a preference of 10. You can use a routing policy to increase the preference of the OSPF route from Router B (making it less preferred), which will cause the route from Router A (with its default preference of 10) to become active, even though its metric is higher. This approach does not require changing the OSPF metric or removing the route from Router A.

Answer

Increase the metric on Router B for that prefix.

Answer

Use a routing policy to reject the OSPF route from Router A.

Answer

Configure a static route to 10.10.10.0/24 pointing to Router A.

Question 5

A router has two routes to the same destination: one with preference 10 and metric 5, and another with preference 15 and metric 3. Which route will be installed in the forwarding table?

Accepted Answer

The route with preference 10.. In Junos, the route preference (administrative distance) is the primary criterion for selecting the best route to a destination. The route with preference 10 is preferred over the route with preference 15, regardless of metric values. The route with preference 10 is installed in the forwarding table.

Answer

The route with metric 3.

Answer

Neither route is installed.

Answer

Both routes are installed if ECMP is enabled.

Question 6

Your company operates a dual-homed network with two Juniper MX routers (R1 and R2) each connected to a different ISP. R1 uses BGP to receive a default route from ISP-A (preference 170), and R2 uses BGP to receive a default route from ISP-B (preference 170). Additionally, both routers have a static default route pointing to a local next-hop (192.0.2.1) with preference 5 for backup. R1 and R2 are connected via an internal link (10.0.0.0/30) and run OSPF to exchange internal routes. You notice that traffic from internal hosts is always exiting via R1's ISP-A link, even when R1's BGP session to ISP-A goes down. The OSPF routes are preferred. You want traffic to fail over to R2's ISP-B link when R1 loses its BGP default. Which configuration change should you make?

Accepted Answer

Configure the static default route with a preference of 180 so that the BGP default routes (pref 170) are preferred when available.. The static default route currently has a preference of 5, making it preferred over the BGP default (preference 170) even when the BGP route is available. By raising the static default's preference to 180 (higher than BGP's 170), the BGP default will be chosen when present, and the static default will only be used as a backup when BGP is unavailable. This ensures traffic fails over to R2's ISP-B link when R1 loses its BGP default, as OSPF will propagate the default from R2.

Answer

Increase the preference of the BGP default routes to 180 so that the static default is always preferred.

Answer

Configure a routing policy on R2 to reject the default route from ISP-B, forcing all traffic through R1.

Answer

Remove the static default route and rely on OSPF to propagate a default route from the router with the active BGP session.

Question 7

Order the steps to configure firewall filters (ACLs) in Junos.

Accepted Answer

First configure match conditions, then configure the action, and finally apply the filter to the interface.. Firewall filters are defined with terms (match conditions and actions) and applied to interfaces.

Answer

First apply the filter to the interface, then configure match conditions, then configure the action.

Answer

First configure the action, then configure match conditions, then apply the filter to the interface.

Answer

First configure match conditions, then apply the filter to the interface, then configure the action.

Question 8

Order the steps to reset the root password on a Junos device via the console.

Accepted Answer

Power cycle the device, interrupt the boot process by pressing the space bar when prompted, select the recovery option (option 2) from the boot menu, set the new root password and reboot.. Root password recovery requires boot interruption and selecting the recovery option from the boot menu.

Answer

Power cycle the device, press Ctrl+C during Junos kernel load to enter the boot loader, type 'boot -s' at the loader prompt, then set the new root password and reboot.

Answer

Connect via SSH, run 'request system root-authentication plain-text-password', enter the new password, then reboot the device.

Answer

Boot the device normally, log in with any credentials, use 'cli' to enter CLI mode, run 'set system root-authentication plain-text-password', then reboot.

Question 9

A network administrator configures a static route on a Juniper device: `set routing-options static route 192.168.100.0/24 next-hop 10.0.0.1`. The administrator verifies the route is present in the routing table but notices it is not active. What is the most likely cause?

Accepted Answer

The next-hop address 10.0.0.1 is not reachable.. A static route becomes active only if the next-hop address is reachable via a directly connected or active route in the routing table. Since the administrator verified the route is present but not active, the most likely cause is that the next-hop 10.0.0.1 is not reachable (e.g., no ARP resolution or no interface with that subnet). Junos marks such routes as hidden or inactive until the next hop is reachable.

Answer

The route is not committed.

Answer

The preference of the static route is higher than 15.

Answer

The destination prefix is already learned via OSPF with a lower metric.

Question 10

A router has two ISIS adjacencies to the same router, both with equal metrics. The router installs both routes in the routing table and performs load balancing. The network team wants to verify that both next-hops are being used for a particular destination. Which command provides this information?

Accepted Answer

`show route forwarding-table destination 10.0.0.0/24`. The `show route forwarding-table destination 10.0.0.0/24` command displays the actual forwarding entries in the Packet Forwarding Engine (PFE), including all next-hops used for load balancing. Unlike the routing table, the forwarding table shows which next-hops are actively installed and used for forwarding traffic, making it the definitive command to verify equal-cost multipath (ECMP) usage.

Answer

`show route 10.0.0.0/24 extensive`

Answer

`show route protocol isis`

Answer

`show route 10.0.0.0/24 detail`

Question 11

A Juniper device receives several routes to the same destination prefix from different routing protocols. Which parameter is used first to select the active route?

Accepted Answer

Route preference (administrative distance). When a Juniper device receives multiple routes to the same destination prefix from different routing protocols, the route preference (also known as administrative distance) is the first tiebreaker used to select the active route. Each protocol has a default preference value (e.g., OSPF internal routes have a preference of 10, while static routes have a preference of 5), and the route with the lowest preference is chosen as active. This occurs before any metric or other path attribute is considered.

Answer

Metric

Answer

AS path length

Answer

Local preference

Question 12

An engineer wants to configure a static route that will be used only if the primary route (learned via OSPF) becomes unavailable. Which feature should be used?

Accepted Answer

Floating static route with a higher preference.. A floating static route is configured with a higher preference (administrative distance) than the OSPF-learned route. Since JUNOS prefers routes with lower preference values, the static route will only be installed in the routing table when the OSPF route is withdrawn, providing a backup path.

Answer

Static route with a lower metric.

Answer

Reverse path forwarding.

Answer

Routing policy.

Question 13

Which two factors determine whether a route is active for a given destination when multiple routes from different protocols exist? (Choose two.)

Accepted Answer

Route preference. B is correct because Junos uses route preference (administrative distance) as the primary tiebreaker when multiple routing protocols offer routes to the same destination. The route with the lowest preference value is installed into the routing table as the active route. D is correct because even if a route has the best preference, it must have a reachable next hop to be considered active; if the next hop is unreachable, the route is hidden and not used.

Answer

Metric

Answer

Route origin

Answer

Local preference

Question 14

Refer to the exhibit. Why is the static route not active?

Accepted Answer

The static route has a higher preference than the OSPF route.. Junos uses route preference (administrative distance) to select the active route when multiple routes to the same destination exist. By default, OSPF has a preference of 10, while a static route has a preference of 5. Since a lower preference value is more preferred, the static route should normally be active. However, the question indicates the static route is not active, which implies the static route's preference has been manually set higher than OSPF's preference (e.g., static route preference > 10), causing OSPF to be selected as the active route.

Answer

The OSPF route has a lower metric.

Answer

The static route's next-hop is not reachable.

Answer

The static route is not committed.

Question 15

Refer to the exhibit. Why is the static route not active?

Accepted Answer

The next-hop address is not reachable in the routing table.. For a static route to be active in the JUNOS routing table, the next-hop address must be reachable via an active route in the routing table. If the next-hop is not reachable, the static route is considered invalid and will not be installed as active, even if the outbound interface is up and the configuration is committed.

Answer

The static route has a high preference.

Answer

The outbound interface is not up.

Answer

The static route is not committed.