JNCIA-JUNOS Routing Fundamentals Practice Test 5 — 15 Questions

Question 1

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.. Route filters prevent mutual redistribution, which is the root cause of routing loops. Options A, C, and D do not address the redistribution issue.

Answer

Use a higher preference for BGP routes.

Answer

Set a lower metric on OSPF routes.

Answer

Increase the OSPF cost on interfaces.

Question 2

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.. The next-hop 10.0.0.1 is not on a directly connected subnet (192.168.1.0/24). For a static route to be installed, the next-hop must be reachable via a directly connected interface unless the 'resolve' option is used. Option A is not a problem. Option C is unlikely. Option D would not prevent route installation if next-hop is reachable.

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 3

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.. Configure the primary with a lower preference and the backup with a higher preference. When the primary is reachable, it is preferred due to lower preference. If it fails, the backup with higher preference becomes active. Option A would not provide deterministic failover. Option C would make backup primary. Option D is not applicable.

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 4

A router is running OSPF and iBGP. Both protocols learn a route to 10.0.0.0/8. The OSPF route is in the routing table with a preference of 10, and the iBGP route has a preference of 170. Which event would cause the iBGP route to become active?

Accepted Answer

Both A and C.. If the OSPF route is withdrawn, the iBGP route becomes active. Also, if the OSPF preference is increased above 170, iBGP wins. So both A and C are valid. Option B does not apply because metric is not compared when preferences differ.

Answer

The OSPF route is withdrawn.

Answer

The iBGP route's metric is lower.

Answer

The OSPF route's preference is changed to 180.

Question 5

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.. Configure a static route with preference 5, which is lower than the default dynamic preferences (e.g., OSPF 10, BGP 170). This ensures the static route is preferred. Option B (preference 15) would be higher than OSPF, so static would not win. Option C could work but is not the simplest. Option D does not affect route selection across protocols.

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 6

Which TWO statements about route preferences in Junos are correct?

Accepted Answer

Direct routes have a default preference of 0.. Default route preferences: direct = 0, static = 5, OSPF internal = 10, BGP = 170. Preferences can be changed using routing policies.

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 7

Which THREE factors are considered when Junos selects the active route among multiple routes to the same destination?

Accepted Answer

Metric. Junos uses preference first; if equal, metric; if still equal, next-hop address as tie-breaker. Route age and interface bandwidth are not considered.

Answer

Route age

Answer

Interface bandwidth

Question 8

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. Valid static route configurations include next-hop (IP, interface), discard, reject, qualified-next-hop, next-table, etc. Invalid include metric, passive, and misspelled keywords.

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 9

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

Accepted Answer

2. The exhibit shows two next hops: 192.168.1.1 and 192.168.2.1. Both are installed as part of an ECMP or redundancy setup.

Answer

4

Answer

3

Answer

1

Question 10

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.. With qualified-next-hop configured with different preferences, the route uses the next-hop with the lowest preference (10) as primary. When that next-hop is unreachable, the route will use the next-hop with preference 20 as the active next-hop.

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 11

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.. The exhibit shows the route is hidden with the reason 'next hop unreachable'. This means the next-hop IP 192.168.100.1 is not reachable via any active route in the routing 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 12

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.. The correct answer is B. A static route requires a reachable next-hop to be installed. If the next-hop is not reachable (e.g., no active route to 10.0.0.1), the route is hidden. Option A is incorrect because static routes have a low preference (5) and would override dynamic routes. Option C is incorrect because a commit would show an error if the configuration failed. Option D is incorrect because the route would be hidden, not in the forwarding table.

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 13

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. The correct answer is B. Junos uses route preference to select the best route. Static routes have a default preference of 5, which is lower than OSPF's internal preference of 10, so the static route is preferred. Option A is wrong because OSPF has a higher preference. Option C is wrong because only one route is active (unless ECMP, but preferences differ). Option D is wrong because one route is active.

Answer

The OSPF route

Answer

Neither route

Answer

Both routes

Question 14

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.. The correct answer is C. Junos supports equal-cost multipath (ECMP) by default for static routes with the same preference and metric. Traffic is load-balanced across both next-hops. Option A is incorrect because active/passive is not default. Option B is incorrect because both routes are considered. Option D is incorrect because traffic is forwarded.

Answer

It uses active/passive selection.

Answer

It uses only the first configured route.

Answer

It drops traffic due to ambiguity.

Question 15

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 correct answer is A. The command 'show route hidden' displays all routes that are not active due to issues like unreachable next-hops, rejection, etc. Option B shows only static routes, not necessarily hidden. Option C shows the forwarding table, not the routing table. Option D shows log messages, not route status.

Answer

show log messages

Answer

show route protocol static

Answer

show route forwarding-table