JNCIA-JUNOS Operational Monitoring and Maintenance Practice Test 2 — 15 Questions

Question 1

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 2

You are the network administrator for a large enterprise with a Juniper MX480 router running Junos 18.2R3. The router has two Routing Engines (RE0 and RE1) in a graceful Routing Engine switchover (GRES) configuration. During a scheduled maintenance window, you need to upgrade the Junos OS to a newer version while minimizing traffic loss. The upgrade process requires a reboot of both REs. You have staged the software on both REs. Which sequence of commands should you use to perform the upgrade with minimal disruption?

Accepted Answer

On RE1 (backup): request system software add re1; request system reboot re1. After reboot, request chassis routing-engine master switch. On RE0 (now backup): request system software add re0; request system reboot re0.. Option D is correct because it performs a hitless upgrade by first upgrading and rebooting the backup RE (RE1), then performing a graceful mastership switch using 'request chassis routing-engine master switch', and finally upgrading and rebooting the former primary (now backup) RE0. This sequence ensures that during each RE reboot, the other RE remains active and continues forwarding traffic, leveraging GRES to maintain state and minimize packet loss.

Answer

On both REs: request system software add <image>; then request system reboot both REs simultaneously.

Answer

On RE0: request system software add re0; on RE1: request system software add re1; then request system reboot both.

Answer

On RE0 (primary): request system software add re0; request system reboot re0. After reboot, on RE1: request system software add re1; request system reboot re1.

Question 3

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 4

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 5

You are managing a Juniper MX240 router at a small ISP. The router has been operating normally for months. This morning, a customer reports intermittent packet loss on their connection, which is served by interface ge-0/0/2. You SSH into the router and run 'show interfaces ge-0/0/2 extensive'. The output shows input errors increasing rapidly, including CRC errors and frame errors. The interface is up/up. You also notice that the interface statistics show a high number of carrier transitions. The cable connecting the router to the customer's CPE was recently replaced by the customer's technician. What is the most likely cause of the errors and the correct action to resolve the issue?

Accepted Answer

Replace the cable with a known good one because CRC and frame errors indicate a physical layer problem such as a damaged cable or loose connector.. CRC and frame errors increasing rapidly, combined with a high number of carrier transitions, are classic symptoms of a physical-layer issue. Since the cable was recently replaced by the customer's technician, the most likely cause is a faulty cable or a loose connector. Replacing the cable with a known good one directly addresses the physical layer problem, which is the root cause of these errors.

Answer

Clear the MAC address table on the router to fix possible MAC flapping issues.

Answer

Administer a 'shutdown' and 'no shutdown' on the interface to reset the line protocol.

Answer

Change the interface speed and duplex settings to auto-negotiate because the errors are due to a mismatch between the router and CPE.

Question 6

Arrange the steps to configure OSPF on a Junos router in the correct order.

Question 7

Arrange the steps to configure a DHCP server on a Junos router.

Question 8

Match each Junos security feature to its description.

Question 9

Match each Junos operational command for monitoring to its output.

Question 10

An administrator notices that the routing table is not updating as expected. Which command should be used to verify the routing table contents?

Accepted Answer

show route. The 'show route' command displays the routing table, which contains all active routes learned via static configuration, direct interfaces, or dynamic routing protocols such as OSPF, IS-IS, BGP, and RIP. If the routing table is not updating as expected, this command allows the administrator to verify the current routes, their next hops, and protocol sources to identify missing or incorrect entries.

Answer

show log

Answer

show system storage

Answer

show interfaces

Question 11

To monitor interface traffic in real-time, which operational command is most appropriate?

Accepted Answer

monitor interface. The 'monitor interface' command in Junos provides real-time, continuous display of interface statistics and traffic counters, updating every second by default. This is the correct operational command for live traffic monitoring, as it refreshes the output dynamically without requiring manual re-entry.

Answer

show interface traffic

Answer

request system reboot

Answer

show log

Question 12

A network engineer needs to check the system's disk space usage. Which command should be used?

Accepted Answer

show system storage. The 'show system storage' command displays disk space usage on Junos devices, including total, used, and available space for each mounted filesystem. This is the correct command for monitoring storage utilization, as it directly reports on the /, /config, and /var partitions critical for system operation.

Answer

show configuration

Answer

show version

Answer

show system uptime

Question 13

After a software upgrade, a router fails to boot with the new image. The engineer suspects the image is corrupted. What is the recommended method to recover?

Accepted Answer

Insert the rescue media and boot from it, then reinstall the image. When a Junos OS image is corrupted and the router fails to boot, the recommended recovery method is to boot from rescue media (such as a USB flash drive or a pre-configured rescue partition) and then reinstall the correct image. This bypasses the corrupted software on the internal storage and provides a clean environment for recovery, ensuring the router can be restored to a functional state.

Answer

Delete the current configuration and reboot

Answer

Reboot the router multiple times

Answer

Use the request system software add command with the force option

Question 14

An administrator wants to verify that BGP neighbors are established. Which command provides a summary of all BGP peer sessions?

Accepted Answer

show bgp summary. The 'show bgp summary' command is correct because it provides a concise, one-line-per-peer overview of all BGP sessions, including the peer IP address, AS number, state (e.g., Established), and counters for prefixes received. This is the standard command in Junos for quickly verifying that all BGP neighbors are in the Established state without the detailed per-neighbor output.

Answer

show bgp neighbor

Answer

show interfaces terse

Answer

show route protocol bgp

Question 15

A technician is troubleshooting a connectivity issue and needs to see the path packets take to a remote host. Which Junos command is appropriate?

Accepted Answer

traceroute. The `traceroute` command in Junos is the correct tool for tracing the path packets take to a remote host. It sends UDP probes with increasing TTL values and listens for ICMP Time Exceeded messages from intermediate routers, revealing each hop along the route. This directly matches the technician's need to see the path packets take.

Answer

monitor interface

Answer

ping

Answer

show route

JNCIA-JUNOS Operational Monitoring and Maintenance Practice Test 2 — 15 Questions

Exhibit

JNCIA-JUNOS Operational Monitoring and Maintenance Practice Test 2 — 15 Questions

Exhibit