JNCIA-JUNOS Practice Test 13 — 15 Questions

Question 1

Refer to the exhibit. An administrator notices the /var partition is nearly full. Which command can be used to safely reclaim disk space?

Accepted Answer

request system storage cleanup. The 'request system storage cleanup' command safely removes old log files, core dumps, and other temporary files that are no longer needed, freeing up space on the /var partition without risking system stability. This is the recommended Junos method for reclaiming disk space because it targets only files that can be safely deleted.

Answer

request system reboot

Answer

delete /var/log/messages

Answer

request system software delete

Question 2

An administrator suspects that an interface is flapping but the router is remote and the connection is intermittent. The administrator wants to monitor the interface status without maintaining an SSH session. Which approach should be used?

Accepted Answer

Configure event-options to trigger on interface down and send syslog. Option A is correct because Junos event-options allows you to define an event policy that triggers on a specific event, such as an interface down transition, and then executes an action like sending a syslog message. This enables asynchronous monitoring without requiring an active SSH session, making it ideal for intermittent connectivity scenarios.

Answer

Use 'monitor interface ge-0/0/0' and rely on terminal persistence

Answer

Use 'monitor start' to capture logs

Answer

Schedule a cron job to run 'show interfaces ge-0/0/0' every minute and log output

Question 3

A technician needs to monitor routing table updates in real time. Which command provides continuous output of routing changes?

Accepted Answer

monitor route. The 'monitor route' command in Junos provides a real-time, continuously updating view of routing table changes as they occur. Unlike static commands that show a snapshot, this command actively tracks route additions, removals, and modifications, making it the correct choice for monitoring routing updates in real time.

Answer

show log messages | match route

Answer

show route

Answer

show route protocol bgp

Question 4

A network administrator is troubleshooting high latency on a link. Which command provides real-time interface statistics?

Accepted Answer

monitor interface traffic. Option B is correct because 'monitor interface traffic' shows live traffic statistics. Option A shows a static brief summary. Option C shows detailed but static output. Option D shows historical log messages.

Answer

show interfaces extensive

Answer

show interfaces terse

Answer

show log messages

Question 5

You are a network administrator for a large enterprise. The Juniper EX4300 switch that serves as the distribution layer for the finance department is experiencing high CPU utilization. Users are complaining of slow network performance. You have accessed the switch via console and notice that the CPU load is consistently above 90%. You need to identify the process causing the high CPU usage. Which command should you use?

Accepted Answer

'show system processes' to list all processes and their CPU usage.. The 'show system processes' command displays a list of all running processes along with their CPU and memory usage, allowing you to identify which process is consuming excessive CPU resources. This is the direct method to pinpoint the offending process on a Juniper EX4300 switch running Junos OS.

Answer

'show task summary' to see kernel task CPU usage.

Answer

'show system resources' to check memory and CPU.

Answer

'show system statistics' to view overall system stats.

Question 6

A network engineer is performing a software upgrade on an MX router. Before upgrading, which operational command should be used to verify the current software version and the upgrade file?

Accepted Answer

show version. The 'show version' command displays the currently running Junos OS version, including the software build and release information. Before upgrading, you must verify the current version to ensure compatibility with the upgrade file, and the upgrade file itself is typically referenced by its filename or path, not shown by this command. To check the upgrade file, you would use 'file list' or 'show system software' to list available packages, but for the current version, 'show version' is the correct operational command.

Answer

show configuration system software

Answer

show system upgrade

Answer

show system software

Question 7

Refer to the exhibit. Which log file will contain messages about authorization events?

Accepted Answer

messages. In Junos, the 'messages' log file (typically /var/log/messages) records system log messages, including authorization events such as user login failures, privilege escalation attempts, and configuration changes. Authorization events are generated by the system's authentication, authorization, and accounting (AAA) framework and are logged at the 'info' severity level by default, which is captured in the messages file. The 'interactive-commands' log file specifically records CLI commands entered by users, not authorization events.

Answer

Both messages and interactive-commands

Answer

Neither

Answer

interactive-commands

Question 8

Refer to the exhibit. How many commits have been made on this device?

Accepted Answer

3. The exhibit shows the output of the 'show system commit' command, which lists each commit made on the device. The output displays three entries, each with a unique commit number (0, 1, 2), indicating that three commits have been performed. Therefore, option A is correct.

Answer

1

Answer

2

Answer

0

Question 9

An administrator needs to grant a user read-only access to the device via SSH. Which configuration should be applied?

Accepted Answer

set system login user guest class read-only. Option B is correct because the 'read-only' class in Junos provides exactly the required level of access: users can view configuration and operational data but cannot make any changes. The 'set system login user guest class read-only' command assigns the predefined 'read-only' login class to the user 'guest', which permits SSH login with read-only privileges. This matches the administrator's requirement precisely.

Answer

set system login user admin class operator

Answer

set system login user readonly class super-user

Answer

set system login user guest class operator

Question 10

What happens when a user issues the 'request system reboot' command without any options?

Accepted Answer

The device prompts for confirmation.. When a user issues the 'request system reboot' command without any options, Junos OS prompts for confirmation before proceeding. This is a safety mechanism to prevent accidental reboots, as the command does not automatically reboot the device immediately or schedule a delayed reboot by default.

Answer

The device reboots after the current commit.

Answer

The device reboots immediately.

Answer

The device schedules a reboot in 5 minutes.

Question 11

Which THREE steps are typically part of a Junos OS upgrade process?

Accepted Answer

Add the image using the request system software add command.. The `request system software add` command is the correct method to initiate a Junos OS upgrade because it stages the new image on the device, performing integrity checks and preparing the system for the next boot. This command is the standard Junos CLI operation for adding a software package, making option B a core step in the upgrade process.

Answer

Remove the previous image.

Answer

Commit the configuration.

Question 12

What is the primary function of the fxp0 interface on a Juniper device?

Accepted Answer

Management interface. The fxp0 interface is a dedicated out-of-band management Ethernet port on Juniper devices, used exclusively for management traffic such as SSH, SNMP, and syslog. It is separate from the data plane and control plane forwarding interfaces, ensuring administrative access remains available even if the routing or forwarding planes are disrupted.

Answer

Internal routing

Answer

Loopback testing

Answer

Data plane forwarding

Question 13

A network administrator needs to remove all configuration changes made since the last commit without affecting the current active configuration. Which command should be used?

Accepted Answer

rollback 0. The `rollback 0` command reverts the candidate configuration to the currently active committed configuration, discarding all uncommitted changes without affecting the active configuration. This is the correct way to undo all modifications made since the last commit while keeping the running configuration intact.

Answer

rollback 1

Answer

deactivate

Answer

delete

Question 14

During a network traffic storm, a Juniper EX switch's CPU utilization spikes to 100%. Which command would best help identify the cause?

Accepted Answer

monitor traffic interface ge-0/0/0. Option A is correct because the 'monitor traffic interface' command captures live packet headers on the specified interface, allowing you to see the type and source of traffic causing the CPU spike. During a traffic storm (e.g., broadcast storm), this command reveals excessive broadcast, multicast, or unknown unicast frames, which are typically the root cause of high CPU utilization on Juniper EX switches.

Answer

show spanning-tree bridge

Answer

show ethernet-switching table

Answer

show interfaces extensive ge-0/0/0

Question 15

A technician needs to upgrade the Junos OS on a device that is part of a redundant cluster. Which approach minimizes traffic disruption?

Accepted Answer

Upgrade one node at a time, ensuring the cluster remains redundant.. Option C is correct because upgrading one node at a time in a redundant cluster ensures that at least one node remains active to handle traffic while the other is being upgraded. This approach maintains cluster redundancy and minimizes traffic disruption, as the active node continues forwarding traffic using the gratuitous ARP or VRRP mechanisms, and the upgraded node rejoins the cluster after reboot.

Answer

Use 'request system software add' on both nodes at the same time.

Answer

Upgrade both nodes simultaneously to reduce maintenance time.

Answer

Use the 'commit synchronize' command to keep configurations in sync after upgrade.

JNCIA-JUNOS Practice Test 13 — 15 Questions

Exhibit

JNCIA-JUNOS Practice Test 13 — 15 Questions

Exhibit