JNCIA-JUNOS Junos OS Fundamentals Practice Test 4 — 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

Answer

Disable SSH

Answer

Change the root password

Question 2

An engineer wants to roll back to the previous configuration without losing the current candidate changes. Which command should be used?

Accepted Answer

rollback 1. The `rollback 1` command reverts the candidate configuration to the most recently committed configuration (the previous commit), while preserving any uncommitted changes in the candidate configuration. This allows the engineer to undo the last commit without discarding current edits, which is exactly what the scenario requires.

Answer

delete

Answer

rollback 0

Answer

commit check

Question 3

A Junos device has multiple configuration files saved. Which command shows the available rollback configurations?

Accepted Answer

show system commit. Option D is correct because the 'show system commit' command displays a list of all committed configuration revisions, including their commit IDs and timestamps, which are used to roll back to a previous configuration. The rollback feature in Junos relies on these stored commit files, and the command explicitly shows the available rollback points.

Answer

show system configuration

Answer

show system rollback

Answer

show configuration | display rollback

Question 4

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

Answer

show system inventory

Answer

show system processes

Question 5

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 . Option C is correct because 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 6

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 7

Which TWO statements about the Junos commit model are true?

Accepted Answer

A commit makes the candidate configuration the active configuration.. Option A is correct because 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 8

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 9

Which TWO statements are true regarding Junos configuration groups?

Accepted Answer

Configuration groups are applied using the apply-groups statement.. Option B is correct because 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 10

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 11

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

Accepted Answer

show configuration. Option C is correct because 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 12

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

Answer

boot device

Answer

boot

Question 13

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. Option B is correct because 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 14

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 device should be upgraded incrementally through each maintenance release before reaching 19.1R1.. Option B is correct because Junos OS requires an incremental upgrade path when the target release is more than one major version ahead. Since 18.1R3 and 19.1R1 are separated by a major version boundary, the device must first be upgraded to an intermediate release (e.g., 18.2 or 18.4) before applying the 19.1R1 image. Skipping major versions can cause incompatibilities in the file system or configuration database.

Answer

The upgrade can be performed directly from 18.1R3 to 19.1R1 using a single junos-install package.

Answer

The command 'request system software add' is used to install the new image.

Answer

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

Question 15

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$

Answer

user@host%

Answer

user@host#

JNCIA-JUNOS Junos OS Fundamentals Practice Test 4 — 15 Questions

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JNCIA-JUNOS Junos OS Fundamentals Practice Test 4 — 15 Questions

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