JNCIA-JUNOS Routing Fundamentals Practice Test 2 — 15 Questions

Question 1

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

Question 2

Which THREE statements are true regarding static routes in Junos?

Accepted Answer

A static route can have a next-hop of a directly connected interface.. A static route can have a next-hop of a directly connected interface, meaning the router will consider the destination as directly reachable out that interface without needing an explicit IP next-hop. This is valid in Junos and is often used for point-to-point links or when the next-hop address is not required.

Answer

Static routes require OSPF to be enabled on the router.

Answer

Static routes automatically generate ICMP redirect messages.

Question 3

Refer to the exhibit. The router has three static routes configured. Which route will be used to forward a packet destined to 172.16.1.100?

Accepted Answer

The static route to 172.16.0.0/16. The router will use the most specific matching route for the destination 172.16.1.100. The static route to 172.16.0.0/16 has a prefix length of 16, which is more specific than the default route (0.0.0.0/0) and the route to 10.0.0.0/8 (which does not match the destination). Therefore, the route to 172.16.0.0/16 is selected based on the longest-prefix-match rule.

Answer

The default route (0.0.0.0/0)

Answer

The router will drop the packet.

Answer

The static route to 10.0.0.0/8

Question 4

You are managing a small enterprise network with one Juniper router and two switches. The router connects to an ISP via ge-0/0/0 and to the internal network via ge-0/0/1. The internal network uses the 192.168.1.0/24 subnet. You need to configure a default route on the router to send all Internet-bound traffic to the ISP gateway at 203.0.113.1. You also want to ensure that internal hosts can reach the Internet. After configuring the default route, you test connectivity from a host on the internal network to an external website, but the ping fails. You verify that the host has an IP address of 192.168.1.100/24 and a default gateway of 192.168.1.1 (the router's internal interface). On the router, you run 'show route 0.0.0.0/0' and see the default route active. You also run 'ping 203.0.113.1' from the router and it succeeds. However, pinging from the host to the ISP gateway fails. What is the most likely cause?

Accepted Answer

Proxy ARP is not enabled on the router's internal interface.. Option D is correct because the host's default gateway (192.168.1.1) is correctly configured, and the router has a working default route to the ISP gateway (203.0.113.1). However, when the host sends a ping to an external IP (e.g., the ISP gateway), the router receives the packet on ge-0/0/1 and routes it out ge-0/0/0. The reply from 203.0.113.1 arrives back at the router's ge-0/0/0, but the router does not have a route for the host's source IP (192.168.1.100) in its routing table (since it's directly connected to ge-0/0/1, but the router needs to send an ARP request for that IP on ge-0/0/1). If Proxy ARP is not enabled on ge-0/0/1, the router will not respond to ARP requests for the host's IP, so the reply packet cannot be delivered to the host. Proxy ARP allows the router to answer ARP requests on behalf of hosts that are not on the same subnet, which is necessary here because the ISP gateway's reply is destined to 192.168.1.100, and the router must act as a proxy to forward that reply to the correct host.

Answer

DNS resolution is failing on the host.

Answer

The host's default gateway is incorrectly configured.

Answer

The default route is not active on the router.

Question 5

Which TWO statements are true about static routes in Junos?

Accepted Answer

Static routes remain in the routing table even if the next hop is unreachable.. Static routes in Junos have a default preference of 5, not 10 (which is the default for OSPF internal routes). They remain in the routing table even if the next hop becomes unreachable because Junos uses a 'passive' route model; the route is only removed if explicitly deleted or if a better route is learned via a routing protocol. This behavior is controlled by the 'no-readvertise' and 'passive' attributes of static routes.

Answer

Static routes have a default preference value of 10.

Answer

Static routes require a routing protocol to be activated.

Answer

Static routes are automatically updated if the network topology changes.

Question 6

Refer to the exhibit. The router has a default static route and a static route to 10.0.0.0/24. An engineer updates the next-hop for the default route from 192.168.1.1 to 192.168.1.2. Which command should the engineer use to verify that the change is active?

Accepted Answer

show route 0.0.0.0/0. Option C is correct because the command 'show route 0.0.0.0/0' displays the routing table entry for the default route, including its next-hop address. After changing the next-hop from 192.168.1.1 to 192.168.1.2, this command confirms the active route has the updated next-hop. It directly verifies the specific prefix that was modified.

Answer

show route 192.168.1.2

Answer

ping 192.168.1.2

Answer

show route protocol static

Question 7

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.. Option D is correct because 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 8

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

Question 9

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

Question 10

Match each Junos routing protocol to its primary characteristic.

Question 11

Match each Junos configuration hierarchy to its function.

Question 12

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 13

An engineer observes that traffic destined to 203.0.113.0/24 is being load-balanced across two equal-cost paths via OSPF. The engineer wants to ensure that all traffic for this prefix uses only one path unless the primary path fails. Which configuration change should be made?

Accepted Answer

Set the OSPF metric on the backup interface to a higher value.. Option B is correct because increasing the OSPF metric on the backup interface makes that path less preferred in the SPF calculation, breaking the equal-cost multipath (ECMP) condition. OSPF selects routes based on the lowest metric; by raising the metric on one interface, the engineer ensures only the lower-metric path is used for forwarding, with automatic failover to the backup path if the primary fails.

Answer

Configure a static route for 203.0.113.0/24 with a lower preference.

Answer

Use policy-options to set a higher preference for one of the paths.

Answer

Modify the load-balance configuration under forwarding-options.

Question 14

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`. Option A is correct because `show route forwarding-table destination` shows the actual next-hops used in the forwarding plane, including load-balanced paths. Option B is wrong because `show route` with detail may show multiple next-hops but not the hardware forwarding decision. Option C is wrong because it shows all ISIS routes, not specific next-hop usage. Option D is wrong because extensive output still shows routing table, not forwarding table.

Answer

`show route 10.0.0.0/24 extensive`

Answer

`show route protocol isis`

Answer

`show route 10.0.0.0/24 detail`

Question 15

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). Option C is correct because route preference (administrative distance) is compared first when routes are from different protocols. Options A and B are BGP-specific and used after preference. Option D is used within the same protocol only.

Answer

Metric

Answer

AS path length

Answer

Local preference