JNCIA-JUNOS Practice Test 3 — 10 Questions

Question 1

A Juniper router is configured with two static routes to the same destination network, both with the same preference. One route has a metric of 5, the other a metric of 10. Which route will be installed in the routing table?

Accepted Answer

The route with metric 5 is installed. In JUNOS, when multiple static routes to the same destination have the same preference (administrative distance), the route with the lower metric is selected for installation in the routing table. Here, metric 5 is lower than metric 10, so the route with metric 5 is installed. This behavior follows the standard route selection process where preference is evaluated first, then metric (also called cost or next-hop metric) as a tiebreaker.

Answer

Neither route is installed because they conflict

Answer

The route with metric 10 is installed

Answer

Both routes are installed with equal preference

Question 2

A network engineer needs to check the operational status of all interfaces on a Juniper device. Which command provides a summary of interface status including link state, protocol state, and error counters?

Accepted Answer

show interfaces terse. Option C is correct because the 'show interfaces terse' command provides a concise summary of all interfaces, displaying the interface name, administrative status (Admin), link state (Link), protocol state (Proto), and a brief description. This command is specifically designed for a quick operational overview, including error counters in the full output when combined with other flags, but the terse output itself focuses on status and protocol state, which directly meets the engineer's requirement.

Answer

show interfaces

Answer

show configuration interfaces

Answer

show interface descriptions

Question 3

Refer to the exhibit. How many next hops are configured for the 192.168.1.0/24 route?

Accepted Answer

2. The correct answer is D because the route 192.168.1.0/24 has two next hops configured: one via 10.0.0.2 and another via 10.0.0.3. This is a case of equal-cost multipath (ECMP) routing, where Junos installs multiple next hops for the same prefix to load-balance traffic across multiple paths.

Answer

0

Answer

3

Answer

1

Question 4

Refer to the exhibit. An engineer configures a new IPv6 address on ge-0/0/0 unit 0 by entering the following commands in configuration mode:

set interfaces ge-0/0/0 unit 0 family inet6 address 2001:db8::2/64
commit

After the commit, the engineer runs 'show interfaces terse ge-0/0/0' and sees only the two original addresses. What is the most likely cause?

Accepted Answer

The engineer did not enter configuration mode before running the 'set' command.. Option B is correct because the engineer likely ran the 'set' command from operational mode (e.g., at the '>' prompt) rather than from configuration mode (e.g., at the '#' prompt). In Junos, 'set' commands only take effect when entered in configuration mode; if entered in operational mode, they are silently ignored or produce an error, and the configuration is not modified. Since the engineer saw no new address after commit, the 'set' command was never applied to the candidate configuration.

Answer

The engineer used 'commit' instead of 'commit confirmed'.

Answer

Junos only allows one IPv6 address per interface.

Answer

The 'set' command requires the 'add' keyword to add a second address.

Question 5

You are a junior network engineer at a company that uses Juniper MX routers. You are troubleshooting a connectivity issue on a branch router. The branch router has two upstream links to the corporate network: ge-0/0/0 (10.1.1.1/30, connected to core router A) and ge-0/0/1 (10.1.1.5/30, connected to core router B). The branch router runs OSPF and has a default route learned from both upstream routers. The routing table shows two equal-cost default routes via both next hops. However, traffic from the branch to the corporate network is experiencing intermittent high latency and some packet loss. You suspect that asymmetric routing is causing issues because the return traffic is not following the same path. You want to influence the router to prefer one upstream link for all traffic to the corporate network. You have decided to adjust the OSPF metric on the branch router to make the link to core router A more preferred. You are in configuration mode on the branch router. Which single configuration change will accomplish this goal?

Accepted Answer

set protocols ospf area 0 interface ge-0/0/1 metric 200. Option C is correct because setting the OSPF metric on interface ge-0/0/1 to a higher value (200) increases the cost of that link, making the default route via ge-0/0/0 (which retains the default OSPF metric of 1 on a Gigabit Ethernet interface) more preferred. This influences the branch router to use the lower-cost path through core router A for all traffic to the corporate network, resolving asymmetric routing issues.

Answer

set interfaces ge-0/0/1 unit 0 family inet cost 200

Answer

set protocols ospf area 0 interface ge-0/0/1 passive

Answer

set interfaces lo0 unit 0 family inet address 10.0.0.1/32 metric 100

Question 6

Refer to the exhibit. What is the purpose of the 'family inet6' configuration on interface ge-0/0/0?

Accepted Answer

To assign a global unicast IPv6 address to the interface.. The 'family inet6' configuration on interface ge-0/0/0 enables IPv6 processing on that interface. Within the 'family inet6' hierarchy, you can assign a global unicast IPv6 address using the 'address' statement. Without 'family inet6', the interface cannot process IPv6 traffic or hold an IPv6 address, making option B correct.

Answer

To enable both IPv4 and IPv6 on the interface.

Answer

To enable IPv6 ARP on the interface.

Answer

To assign a link-local IPv6 address to the interface.

Question 7

Which TWO statements correctly describe the use of the 'monitor traffic' command in Junos?

Accepted Answer

It can filter packets using the 'matching' option to capture only specific traffic.. Option B is correct because the 'monitor traffic' command in Junos supports a 'matching' option that allows you to specify a filter (e.g., 'matching "icmp"') to capture only packets that match the given criteria, reducing noise and focusing on specific traffic types. Option C is correct because 'monitor traffic interface <interface-name>' captures packets on a specified interface and displays them in real-time, which is useful for live troubleshooting.

Answer

It captures packets from the Routing Engine only.

Answer

It requires a reboot to start capturing packets.

Answer

It reads packets from a previously saved pcap file.

Question 8

Refer to the exhibit. A network engineer sees repeated 'PFE interrupt error' messages in the log for fpc0. What is the most likely impact and recommended action?

Accepted Answer

Replace the line card (FPC0) as it is experiencing hardware failures causing traffic loss.. The 'PFE interrupt error' message indicates a hardware-level failure on the Packet Forwarding Engine (PFE) of FPC0. Since the PFE is responsible for forwarding packets, such errors typically cause traffic loss or drops. The recommended action is to replace the line card (FPC0) because persistent PFE interrupt errors are symptomatic of a hardware fault that cannot be resolved by software resets or upgrades.

Answer

Remove and reinsert the PIC on FPC0 to reseat the connection.

Answer

Restart the PFE process using 'restart pfe' command.

Answer

Perform a software upgrade on the router to fix a known bug.

Question 9

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 10

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