JN0-106 Junos OS Fundamentals Practice Test 3 — 15 Questions

Question 1

Refer to the exhibit. An administrator notices repeated failed login attempts. What should be configured to mitigate this attack?

Accepted Answer

Configure a firewall filter to block the source IP. A firewall filter can block traffic from the source IP address of the repeated failed login attempts, preventing further access from that host. This is a direct and immediate mitigation against an ongoing brute-force attack, as it stops the attacker's traffic at the network layer before it reaches the SSH or login service.

Answer

Set login retry limit

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Disable SSH

Answer

Change the root password

Question 2

Which operational command displays the system's current time and date?

Accepted Answer

show system uptime. The correct command to display the system's current time and date in Junos is 'show system uptime'. This command outputs the current time and date, along with how long the system has been running (uptime), the number of users, and the load averages. It is the standard operational command for checking the system clock on Juniper devices.

Answer

show system time

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show system inventory

Answer

show system processes

Question 3

A device is configured with multiple routing instances. An engineer needs to view the ARP table for a specific routing instance. Which command should be used?

Accepted Answer

show arp instance . The `show arp instance ` command is the Junos OS syntax to display the ARP table for a specific routing instance. In Junos, routing instances create separate forwarding tables, and the ARP cache is per-instance; this command targets the instance's ARP entries directly.

Answer

show arp routing-instance <instance-name>

Answer

show arp

Answer

show route table <instance-name>.inet.0

Question 4

Which TWO statements about the Junos commit model are true?

Accepted Answer

A commit makes the candidate configuration the active configuration.. The Junos commit model uses a two-phase process: changes are made to the candidate configuration, and the `commit` command activates that candidate configuration as the new active configuration. This ensures that changes are not applied until explicitly committed, providing a safe and predictable way to modify the device's operational state.

Answer

The commit command is used to discard changes.

Answer

A commit validation is performed automatically before commit.

Answer

Multiple candidates can be active simultaneously.

Question 5

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 correct steps for a Junos OS upgrade are: B: Use `request system software add` to stage and install the new image; D: Validate the new image (though the add command often performs validation, a separate validation step is also typical); E: Reboot the device to load the new image. Option A is not needed because Junos automatically handles the old image, and option C is unrelated to the software upgrade process—commit applies to configuration changes, not software installation.

Answer

Remove the previous image.

Answer

Commit the configuration.

Question 6

Which TWO statements are true regarding Junos configuration groups?

Accepted Answer

Configuration groups are applied using the apply-groups statement.. The `apply-groups` statement is the explicit mechanism used to reference and apply a configuration group to a specific hierarchy or the entire configuration. Without `apply-groups`, the group definition has no effect.

Answer

Configuration groups never override existing settings.

Answer

Configuration groups are only useful for interface configuration.

Answer

Configuration groups are applied automatically to all hierarchies.

Question 7

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 8

An engineer wants to view the current active configuration file that the device is using. Which command displays this information?

Accepted Answer

show configuration. The 'show configuration' command displays the current active configuration that the device is using, which is the committed configuration stored in /config/juniper.conf.gz. This command reads the active configuration file directly from the file system, showing the exact operational configuration that Junos applies to the device.

Answer

show configuration candidates

Answer

show system commit

Answer

show configuration | display set

Question 9

A Junos device fails to boot and enters the loader prompt. Which command should be used to boot the device into the Junos kernel from the loader prompt?

Accepted Answer

boot /kernel. When a Junos device fails to boot and drops to the loader prompt (U-Boot or similar), the correct command to manually load the Junos kernel is 'boot /kernel'. This command instructs the bootloader to locate and execute the kernel file from the default filesystem path. Option D is correct because it specifies the full path to the kernel, which is required at the loader prompt to initiate the Junos OS boot process.

Answer

load kernel

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boot device

Answer

boot

Question 10

A technician is troubleshooting a device that has an inconsistent configuration. They need to revert to the configuration that was committed exactly two commits ago. Which command sequence accomplishes this?

Accepted Answer

rollback 2 followed by commit. The `rollback 2` command reverts the candidate configuration to the state it was in two commits ago, but the change is not applied until a `commit` is issued. This two-step sequence (rollback followed by commit) is required to make the reverted configuration active. Without the commit, the device continues running the current active configuration.

Answer

rollback 2

Answer

commit confirmed 2

Answer

rollback 3

Question 11

An organization plans to upgrade Junos from version 18.1R3 to 19.1R1. The device currently runs on 18.1R3. Which statement is true regarding the upgrade process?

Accepted Answer

The upgrade can be performed directly from 18.1R3 to 19.1R1 using a single junos-install package.. Junos OS allows direct upgrades to a subsequent major release without requiring every maintenance release in between. From 18.1R3, you can install the 19.1R1 package directly using 'request system software add' and then reboot. A reboot is required to activate the new image, and the device will not remain operational during the upgrade process.

Answer

The device should be upgraded incrementally through each maintenance release before reaching 19.1R1.

Answer

The device will remain operational during the upgrade process without a reboot.

Question 12

A user needs to access the operational mode on a Junos device. What is the default prompt in operational mode?

Accepted Answer

user@host>. In Junos OS, the default prompt in operational mode is `user@host>`. The `>` character indicates that the device is ready to accept operational commands, such as `show` or `ping`, which do not alter the configuration. This is a fundamental distinction in Junos, where operational mode is for monitoring and troubleshooting, while configuration mode uses the `#` prompt.

Answer

user@host$

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user@host%

Answer

user@host#

Question 13

An administrator wants to ensure that if a network interface fails, the routing protocol process automatically restarts. Which Junos feature should be configured?

Accepted Answer

Graceful Restart. Graceful Restart is a high-availability feature that mitigates disruption when the routing protocol process (rpd) restarts, but it does not initiate restarts based on interface failures. Auto-restart (A) automatically restarts a failed process, but it is triggered by process failure, not interface failure. BFD (C) detects failures, and NSR (B) handles RE switchover—neither triggers rpd restart. The premise of the question is flawed because interface failures do not normally cause rpd to restart.

Answer

auto-restart

Answer

Nonstop Routing (NSR)

Answer

Bidirectional Forwarding Detection (BFD)

Question 14

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.. 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.

Question 15

Which command saves the current operational state information to a file that can be provided to Juniper support for troubleshooting?

Accepted Answer

request support information. The 'request support information' command collects a comprehensive snapshot of the current operational state, including configuration, logs, routing tables, and interface statistics, and packages it into a file (e.g., /var/tmp/support-info-date-time.tgz) that can be directly provided to Juniper support for troubleshooting. This is the standard Junos method for gathering diagnostic data.

Answer

monitor traffic

Answer

show system information

Answer

file copy