JN0-106 Operational Monitoring and Maintenance Practice Test 2 — 15 Questions

Question 1

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?

Choose an answer to begin — your selection is scored in the full session.

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.. 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 2

Which THREE 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.. The 'monitor traffic' command supports a 'matching' option that allows you to specify a BPF filter to capture only specific traffic. Option C is correct because 'monitor traffic interface ' captures packets on a specific interface and displays them in real-time. Option E is correct because the 'monitor traffic' command can read packets from a previously saved pcap file using the 'file' option (e.g., 'monitor traffic file '), which is useful for offline analysis.

Answer

It captures packets from the Routing Engine only.

Answer

It requires a reboot to start capturing packets.

Question 3

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 4

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

Accepted Answer

Step 1: Configure the router ID. Step 2: Configure the OSPF area and assign interfaces. Step 3: Verify OSPF neighbor relationships.. OSPF requires a router ID and interfaces assigned to areas. Verification shows neighbor relationships.

Answer

Step 1: Configure the OSPF area and assign interfaces. Step 2: Configure the router ID. Step 3: Verify OSPF neighbor relationships.

Answer

Step 1: Verify OSPF neighbor relationships. Step 2: Configure the router ID. Step 3: Configure the OSPF area and assign interfaces.

Answer

Step 1: Configure the router ID. Step 2: Verify OSPF neighbor relationships. Step 3: Configure the OSPF area and assign interfaces.

Question 5

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

Accepted Answer

Step 1: Enable DHCP services. Step 2: Configure a DHCP pool with subnet and range. Step 3: Set DHCP options (gateway, DNS). Step 4: Exclude specific addresses.. The correct sequence for configuring a DHCP server on a Junos router is to first enable DHCP services, then define a pool with subnet and range, set DHCP options like gateway and DNS, and finally exclude specific addresses. This ensures all dependencies are met and the configuration is applied logically.

Answer

Step 1: Configure a DHCP pool with subnet and range. Step 2: Enable DHCP services. Step 3: Set DHCP options. Step 4: Exclude specific addresses.

Answer

Step 1: Enable DHCP services. Step 2: Set DHCP options. Step 3: Configure a DHCP pool with subnet and range. Step 4: Exclude specific addresses.

Answer

Step 1: Enable DHCP services. Step 2: Configure a DHCP pool with subnet and range. Step 3: Exclude specific addresses. Step 4: Set DHCP options.

Question 6

Match each Junos security feature to its description.

Accepted Answer

Screen: Provides protection against various types of network attacks. The correct matches are: Screen for attack protection, Zone for grouping interfaces, Security Policy for traffic rules, and NAT for address translation. Common confusions include mixing Screen with Security Policy or Zone with NAT.

Answer

Screen: Defines rules to permit or deny traffic based on source, destination, application

Answer

Zone: Translates private IP addresses to public IP addresses

Question 7

Match each Junos operational command for monitoring to its output.

Accepted Answer

show interfaces: Displays interface status and packet counts. The correct matches are: show interfaces with interface status, show route with routing table, and show log with system logs. Common confusions involve swapping outputs among these commands.

Answer

show interfaces: Displays routing table entries

Answer

show version: Displays interface status

Question 8

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 9

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 10

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 11

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 12

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 13

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

Question 14

During a maintenance window, an engineer plans to replace a line card. Which command sequence is most appropriate to gracefully deactivate the card before removal?

Accepted Answer

request chassis pic slot offline; request chassis fpc offline. The 'request chassis fpc offline' command gracefully deactivates the Flexible PIC Concentrator (FPC) by stopping traffic, closing sessions, and powering down the line card safely. The 'request chassis pic slot offline' command is used for individual PICs, but for a full line card (FPC), the FPC-level command is the appropriate sequence to ensure no traffic disruption or hardware damage during removal.

Answer

delete interfaces fxp0

Answer

set interfaces <name> disable

Answer

request system reboot

Question 15

An administrator observes that the router's CPU utilization is consistently high. Which command helps identify which process is consuming the most CPU?

Accepted Answer

show system processes extensive. 'show system processes extensive', is correct because it displays detailed CPU utilization statistics for each running process on a Junos device, including the percentage of CPU time consumed. This allows the administrator to identify which specific process (e.g., routing protocol daemon, SNMP, or management process) is causing the high CPU load, enabling targeted troubleshooting.

Answer

show log messages

Answer

show system resource

Answer

show chassis routing-engine