JN0-106 Routing Fundamentals Practice Test 3 — 15 Questions

Question 1

What is the default preference value of a directly connected (direct) route in JunOS?

Accepted Answer

0. In JunOS, directly connected routes have a default preference value of 0, which is the highest possible preference (lowest numerical value). This ensures that directly connected routes are always preferred over routes learned from any dynamic routing protocol, as they represent interfaces that are directly reachable on the local device.

Answer

10

Answer

170

Answer

100

Question 2

An administrator suspects that routing protocol updates are being sent to an incorrect next-hop. Which command can be used to capture and analyze the routing protocol packets on an interface?

Accepted Answer

monitor traffic interface ge-0/0/0.0. The 'monitor traffic interface' command in Junos captures live packets on a specified interface, allowing the administrator to inspect routing protocol packets (e.g., OSPF, BGP) in real time. This is the only option that directly captures and displays packet-level data to verify the next-hop IP address in routing protocol updates.

Answer

show log messages | match ospf

Answer

show route forwarding-table

Answer

show ospf neighbor detail

Question 3

Which TWO statements are true about the default route in JunOS? (Choose two.)

Accepted Answer

It has a prefix of 0.0.0.0/0. The default route in JunOS is represented by the prefix 0.0.0.0/0, which matches any destination IP address. This is the standard IPv4 default route notation used in routing tables to forward packets when no more specific route exists.

Answer

It can only be learned dynamically

Answer

Its default preference is 0

Answer

It is always present in the routing table

Question 4

Which THREE conditions must be met for a route to be considered active in the JunOS routing table? (Choose three.)

Accepted Answer

The route is preferred based on protocol preference. JunOS uses a route's protocol preference (administrative distance) to select the best route among multiple routes for the same prefix from different routing protocols. The route with the lowest preference value is considered the most preferred and becomes active, provided other conditions are met.

Answer

The route is the only route for the prefix

Answer

The route is from a trusted protocol

Question 5

Which TWO factors are directly used when comparing route preferences in JunOS? (Choose two.)

Accepted Answer

Metric (or cost). In JunOS, route preference (also known as administrative distance) is a value assigned to a routing protocol or a static route to determine which route is preferred when multiple protocols provide a route to the same destination. The route with the lowest preference value is selected. Additionally, when comparing routes from the same protocol, the metric (or cost) is used as the tiebreaker. Therefore, both preference value and metric are directly used in JunOS route preference comparisons.

Answer

Next-hop reachability

Answer

Number of hops

Answer

Prefix length

Question 6

Refer to the exhibit. How many active routes exist for 10.1.1.0/24?

Accepted Answer

1. The route 10.1.1.0/24 appears in the routing table with a next-hop of 192.168.1.1 and a preference of 5 (directly connected). Only one active route is present because the routing table shows a single entry for this prefix. Junos selects the active route based on the lowest preference value; here, there is no competing route, so only one route is active.

Answer

2

Answer

0

Answer

3

Question 7

A router has multiple equal-cost paths to the same destination. Which statement describes how Junos load balances traffic across these paths?

Accepted Answer

Junos uses per-flow load balancing based on source and destination IP and port.. When multiple equal-cost paths exist, Junos uses per-flow load balancing by default. The default hash algorithm uses the source and destination IP addresses (Layer 3) to select a next hop. Source and destination ports are not included unless you explicitly configure load-balancing hash keys to include Layer 4 information. This ensures packets of the same flow are consistently forwarded to the same next-hop.

Answer

Junos uses the route with the lowest next-hop IP.

Answer

Junos installs only one route and ignores the others.

Answer

Junos uses per-packet load balancing by default.

Question 8

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?

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 9

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 10

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

The OSPF route is withdrawn.. Both A and D correctly cause the iBGP route to become active. The question must be updated to either 'Which two events' or to remove one of the correct options. The current answer key with both is not appropriate for a single-answer exam question.

Answer

Both A and C.

Answer

The iBGP route's metric is lower.

Question 11

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

Accepted Answer

Metric. Junos uses the route's metric (also called cost) as a tiebreaker when multiple routes have the same preference. The route with the lowest metric is selected as active. This is a standard behavior for protocols like OSPF (cost) and RIP (hop count).

Answer

Route age

Answer

Interface bandwidth

Question 12

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. The `discard` action is a valid next-hop type for a static route in Junos, which silently drops traffic destined for the 10.0.0.0/8 network without sending an ICMP unreachable message. Option C is correct because `qualified-next-hop` allows you to specify an alternate next-hop with a different preference value, which is a standard Junos feature for creating floating static routes.

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 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. 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 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.. 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 15

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). An aggregate route requires at least one contributing route (a more specific route within the aggregate's range) to become active in the routing table. Without a contributing route, the route remains inactive. Option A is incorrect because a directly connected interface on that subnet is not required and would not make the aggregate active. Option B is incorrect because a static route to the aggregate prefix is not required and would not contribute. Option D is false because the aggregate is not always active; it needs a contributor.

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.