JNCIA-JUNOS Timed Practice Test 1 — 10 Questions

Question 1

A junior engineer needs to collect a snapshot of the current system state, including routing tables, interfaces, and configuration, for a support ticket. Which command achieves this?

Accepted Answer

request support information. The 'request support information' command is the correct choice because it collects a comprehensive snapshot of the current system state, including routing tables, interface details, configuration, logs, and other operational data into a single archive file. This is specifically designed for support tickets, as it bundles all relevant diagnostic information in one step, unlike individual show commands that only capture partial data.

Answer

show configuration

Answer

show interfaces

Answer

show route

Question 2

A network engineer is troubleshooting a connectivity issue and wants to see the active routes in the routing table. Which Junos CLI command should they use?

Accepted Answer

show route. The 'show route' command displays the active routing table entries, including directly connected, static, and dynamic routes learned via protocols like OSPF, BGP, or IS-IS. This is the correct command to view the active routes the device uses for forwarding traffic.

Answer

show log messages

Answer

show configuration

Answer

show interface

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

Which TWO attributes are used by Junos to select the active route among multiple routes to the same destination?

Accepted Answer

Metric. Junos uses the route preference (also known as administrative distance) as the primary attribute to select the active route among multiple routes to the same destination. If multiple routes have the same preference, Junos then compares the metric (also called cost or protocol-specific metric) to break the tie. Preference is a local, configurable value that ranks the trustworthiness of the routing protocol source, while metric is a protocol-specific value (e.g., OSPF cost, RIP hop count) used within the same protocol.

Answer

Protocol type

Answer

Next hop address

Answer

AS path length

Question 5

What is the default preference of a direct route in Junos?

Accepted Answer

0. Direct routes in Junos have a default preference of 0, which is the highest possible preference (lowest numerical value). This ensures that directly connected routes are always preferred over any other route type, including static routes (preference 5) and OSPF internal routes (preference 10). The preference value is used by Junos to select the best route when multiple routes exist to the same destination.

Answer

10

Answer

5

Answer

15

Question 6

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 7

A network engineer is designing a redundant network with two Juniper routers running VRRP. The virtual IP address is 10.0.0.1. Both routers are configured as VRRP group 1. What is the purpose of the 'priority' parameter in VRRP configuration?

Accepted Answer

It determines the master router election.. In VRRP, the 'priority' parameter (range 1-254, default 100) is used to elect the master router. The router with the highest priority becomes the master for the virtual IP address 10.0.0.1, ensuring redundancy by taking over traffic forwarding if the current master fails.

Answer

It sets the interval for VRRP advertisements.

Answer

It determines the virtual MAC address.

Answer

It changes the virtual IP address.

Question 8

Which TWO statements correctly describe the behavior of the 'commit confirmed' command in Junos?

Accepted Answer

The confirmation timeout can be modified by specifying a number of minutes.. Option A is correct because the `commit confirmed` command in Junos accepts an optional numeric argument (in minutes) to override the default confirmation timeout. For example, `commit confirmed 10` sets a 10-minute window during which the administrator must issue a `commit` to make the changes permanent; otherwise, the system automatically rolls back to the previous active configuration.

Answer

The default confirmation timeout is 5 minutes.

Answer

It requires a reboot to revert to the previous configuration.

Answer

It stages the configuration in the candidate configuration but does not apply it until confirmed.

Question 9

Based on the exhibit, which protocol is enabled on interface ge-0/0/0.0?

Accepted Answer

MPLS. The exhibit shows that interface ge-0/0/0.0 has the 'family mpls' statement configured under it, which enables MPLS on that interface. MPLS is explicitly enabled at the protocol family level, allowing the interface to participate in MPLS label switching.

Answer

IS-IS

Answer

BGP

Answer

OSPF

Question 10

A network engineer is troubleshooting a reachability issue between two directly connected routers. Both routers have IP addresses configured on their interfaces and the interfaces are up. Which command would the engineer use to verify the routing table entry for the remote network?

Accepted Answer

show route. The 'show route' command displays the routing table, which contains all active routes learned via static configuration, direct connections, or dynamic routing protocols. To verify the routing table entry for a specific remote network, this command shows the next-hop IP address, interface, and route preference/metric, directly confirming whether the remote network is reachable.

Answer

show interfaces terse

Answer

show configuration interfaces

Answer

show arp