JNCIA-JUNOS Routing Fundamentals Practice Test 3 — 15 Questions

Question 1

A network administrator configures the following: `set routing-options static route 0.0.0.0/0 next-hop 192.168.1.1`. After committing, the administrator notices that the default route is not active. What could be the reason?

Accepted Answer

The next-hop 192.168.1.1 is not reachable.. Option D is correct because the next-hop address may not be reachable. Option A is wrong because if a DHCP default route existed, the static route would be preferred due to lower preference. Option B is wrong since a higher preference number makes a route less preferred, but the route would still be active if it's the only route. Option C is wrong because static routes are automatically placed in the forwarding table if active.

Answer

The route preference is set to 170.

Answer

The route is not exported into the forwarding table.

Answer

The router already has a default route learned via DHCP.

Question 2

A static route with a next-hop of 10.0.0.1 is configured, but the route is not appearing in the active routing table. The output of `show route 10.0.0.1` shows that 10.0.0.1 is reachable via an OSPF route with preference 10. What is the most likely reason the static route is not active?

Accepted Answer

The static route is configured with a qualified-next-hop that fails.. Option A is correct because the static route may be configured with a qualified-next-hop that is not satisfied. Option B is wrong because static route preference (5) is lower than OSPF (10), so static should be active. Option C is wrong because next-hop reachable via OSPF should allow static route to be active. Option D is wrong because metric is not compared across protocols.

Answer

The OSPF route has a lower metric than the static route.

Answer

The static route's next-hop is not directly connected.

Answer

The static route has a higher preference than OSPF.

Question 3

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.. Option B is correct because a floating static route uses a higher preference so it is less preferred than OSPF and only becomes active when OSPF fails. Option A is wrong because metric is not comparable across protocols. Option C is wrong because RPF is unrelated. Option D is wrong because routing policy is too broad and not the specific feature.

Answer

Static route with a lower metric.

Answer

Reverse path forwarding.

Answer

Routing policy.

Question 4

A Juniper MX router is configured with multiple routing instances. In which scenario would an interface be automatically placed in a routing instance?

Accepted Answer

When the interface is configured under the instance's `interface` statement.. Option C is correct because interfaces must be explicitly configured under the routing instance's `interface` statement. Option A is wrong because IP addressing alone does not assign to an instance. Option B is wrong because the default instance is the master instance, not an automatic placement into another instance. Option D is wrong because virtual-router type also requires explicit configuration.

Answer

When the interface is configured with an IP address from the instance's address family.

Answer

When the interface is associated with the default instance.

Answer

When the routing instance type is virtual-router and the interface is a physical interface.

Question 5

A network engineer is troubleshooting a BGP routing issue. The router receives a route to 172.16.0.0/16 from two BGP peers with different local preferences. The route from peer A has local preference 200, and from peer B has local preference 100. The router selects the route from peer A. What is the next step in BGP path selection if the local preferences were equal?

Accepted Answer

Compare the AS path length.. Option D is correct because after local preference, BGP compares AS path length. Options A, B, and C are compared later in the BGP path selection process.

Answer

Compare the MED.

Answer

Compare the IGP metric to the next-hop.

Answer

Compare the origin code.

Question 6

Which two statements are true about static routes on Juniper devices? (Choose two.)

Accepted Answer

A static route with a next-hop of an IP address requires that the next-hop be reachable.. Options B and E are correct. Option A is false because a static route with a next-hop of an interface is not active if the interface is down. Option C is false because static routes can be used for load balancing. Option D is false because a lower preference number indicates a more preferred route.

Answer

A static route with a next-hop of an interface will be active even if the interface is down.

Answer

A static route with a preference of 10 is preferred over a static route with a preference of 5.

Answer

Static routes cannot be used for load balancing.

Question 7

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 8

A route is present in the routing table but is not active. Which three conditions could explain this? (Choose three.)

Accepted Answer

A route with a lower preference exists for the same destination.. A route with a lower preference (administrative distance) is preferred for the same destination prefix. In JUNOS, the route with the lowest preference value is installed as the active route in the forwarding table. If a route has a higher preference, it remains in the routing table as a backup but is not marked as active.

Answer

The route is hidden due to a firewall filter.

Answer

The route is an aggregate route.

Question 9

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

Accepted Answer

The static route has a higher preference than the OSPF route.. Option C is correct because the static route has a preference of 15, which is higher than OSPF's preference of 10, making OSPF the active route. Option A is wrong because metric is not compared across protocols. Option B is wrong because the next-hop is reachable (via ge-0/0/0.0). Option D is wrong because the route is present in the table, so it is committed.

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 10

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

Accepted Answer

The next-hop address is not reachable in the routing table.. Option A is correct because the static route's next-hop (10.10.10.1) is not present in the routing table. Option B is wrong because the preference is low (5). Option C is wrong because the interface is shown in the route entry, implying it is up. Option D is wrong because the route is present, so it is committed.

Answer

The static route has a high preference.

Answer

The outbound interface is not up.

Answer

The static route is not committed.

Question 11

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

Accepted Answer

The route was manually configured.. Option B is correct because 'user' in the forwarding table indicates a manually configured route (e.g., static). Option A is wrong because protocol-learned routes show 'other' or specific protocol. Option C is wrong because default routes generated by the router (e.g., through router advertisement) would not show as 'user'. Option D is wrong because kernel routes show as 'kern'.

Answer

The route is from the kernel.

Answer

The route is a default route generated by the router.

Answer

The route was learned from a routing protocol.

Question 12

A network administrator configures a default route using 'set routing-options static route 0.0.0.0/0 next-hop 10.0.0.1 preference 10' and later enables OSPF which also advertises a default route with default preference 150. Which route becomes active in the routing table?

Accepted Answer

Static route to 0.0.0.0/0 with next-hop 10.0.0.1. The static route with preference 10 is preferred over the OSPF route with preference 150 because JunOS selects the route with the lowest preference value. Option A is correct. Option B is incorrect because higher preference is less preferred. Option C is incorrect because ECMP requires equal cost routes, not different preference. Option D is incorrect because the static route is valid.

Answer

Neither route becomes active due to conflicting protocols

Answer

Both routes are active for ECMP load balancing

Answer

OSPF route to 0.0.0.0/0

Question 13

An engineer configures a static route to 192.168.0.0/16 with next-hop 172.16.1.1. The router has a directly connected route for 172.16.1.0/30 via interface ge-0/0/0.1. However, 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. A hidden static route typically means the next-hop is not reachable. Option D correctly identifies this. Option A is incorrect because high preference does not cause hidden; it may not be active but still visible. Option B is incorrect because a discard route would be flagged as 'discard'. Option C is incorrect because the route is committed if it appears in the configuration.

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 14

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. The loop occurs because the OSPF route (preference 10) is active, pointing a BGP next-hop that causes a recursive loop. By increasing the OSPF route's preference to 175 (higher than BGP's 170), the BGP route becomes active, and if the BGP next-hop is reachable via a non-looping path, the loop stops. Option A is correct. Option B is incorrect because setting next-hop to self does not prevent the OSPF route from being used. Option C is incorrect because a static route would override BGP and would not be received via BGP. Option D is incorrect because route reflection does not address the preference conflict.

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 15

Which JunOS command displays the active route for a specific destination along with the outgoing interface?

Accepted Answer

show route 10.0.0.1 exact. The 'show route <prefix> exact' command displays the active route including the next-hop and interface. Option C is correct. Option A is not a valid command. Option B shows all routes for that prefix, not just the active one. Option D shows only static routes.

Answer

show route 10.0.0.1 active-path

Answer

show route 10.0.0.1 protocol static

Answer

show route 10.0.0.1 table inet.0