JN0-106 Junos OS Fundamentals Practice Test 2 — 15 Questions

Question 1

Match each Junos file system directory to its content.

Accepted Answer

/config: Contains active configuration files. These are key directories in the Junos file system. Correct matches: /config (configuration), /var (variable data), /tmp (temporary). Common confusions involve /altroot and /packages.

Answer

/altroot: Contains software packages

Answer

/packages: Backup root filesystem

Question 2

Which command displays the current hostname of a Junos device?

Accepted Answer

show system host-name. The command 'show system host-name' is the correct operational mode command to display the current hostname configured on a Junos device. It retrieves the hostname from the active configuration and displays it in the output, confirming the device's identity on the network.

Answer

show chassis hardware

Answer

show configuration system host-name

Answer

show system uptime

Question 3

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. 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 4

Which command is used to view the terminal history of commands entered by the user?

Accepted Answer

show cli history. The 'show cli history' command displays the list of previously entered CLI commands in the current session, allowing users to recall and re-execute them. This is a Junos-specific command that provides a terminal history feature, distinct from the commit history or system logs.

Answer

show system commit

Answer

show configuration

Answer

show log messages

Question 5

An engineer suspects that a recent software upgrade caused a compatibility issue. Which command should be used to revert the Junos OS to the previous version?

Accepted Answer

request system software rollback. The 'request system software rollback' command is the correct method to revert the Junos OS to the previously installed version. This command triggers a reboot and loads the previous software set from the /altroot partition, effectively undoing the upgrade while preserving the configuration.

Answer

rollback 0

Answer

request system reboot

Answer

request system software delete jinstall-*.tgz

Question 6

Refer to the exhibit. Which filesystem should the administrator investigate to free up disk space?

Accepted Answer

/var. The /var filesystem on Junos devices stores system logs, core dumps, and temporary files. When disk space is low, /var is the most common culprit because it contains rotating log files (e.g., messages, interactive-commands) and crash data that can accumulate rapidly. The administrator should investigate /var to free up space by clearing old logs or core files.

Answer

/config

Answer

/ (root)

Answer

/dev

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

Which TWO statements are true about the Junos OS boot process?

Accepted Answer

The routing engine initializes after the kernel loads.. The routing engine initializes after the kernel loads; the kernel starts processes including the routing engine. Option D is correct because the boot loader (e.g., U-Boot) loads the Junos kernel from the boot device into memory. Option E is incorrect: the kernel does not mount the root file system; the root file system is already accessible from the boot device and the kernel accesses it directly without a separate mount step.

Answer

The forwarding engine is initialized before the kernel.

Answer

The configuration is loaded from /config before the kernel starts.

Answer

The kernel mounts the root file system.

Question 10

Which THREE actions can be performed in operational mode on a Junos device?

Accepted Answer

Ping a remote host. Operational mode in Junos is used for monitoring, troubleshooting, and managing the device, not for making configuration changes. The 'ping' command is a standard operational mode command that sends ICMP echo requests to a remote host to test network connectivity, making option B correct.

Answer

Commit configuration changes

Answer

Configure interface IP addresses

Question 11

Which TWO commands are used to install and remove software packages on a Junos device?

Accepted Answer

request system software delete. The `request system software add` command is used to install a new software package on a Junos device, while `request system software delete` is used to remove an installed software package. These are the two primary operational mode commands for software lifecycle management in Junos OS.

Answer

request system software rollback

Answer

show system software

Answer

request system reboot

Question 12

Which command shows the operational status of all interfaces in a brief format?

Accepted Answer

show interfaces terse. The 'show interfaces terse' command displays a brief, one-line summary of each interface, including its administrative status (up/down), link status, protocol status, and configured IP addresses. This is the correct command for a concise overview of all interfaces' operational state, as specified in the Junos OS documentation.

Answer

show interfaces statistics

Answer

show interfaces detail

Answer

show configuration interfaces

Question 13

What is the default behavior when a user logs in to a Junos device and enters configuration mode?

Accepted Answer

The user can edit the candidate configuration.. When a user enters configuration mode on a Junos device, they are placed into a private copy of the candidate configuration. This allows the user to make changes without affecting the active configuration until a commit operation is performed. Option B correctly describes this default behavior.

Answer

The user must first commit before making changes.

Answer

The user can only view the configuration.

Answer

The user directly modifies the active configuration.

Question 14

An engineer needs to copy a configuration from one device to another. Which command should be used to export the current active configuration in a mergeable format?

Accepted Answer

show configuration | display set. The 'show configuration | display set' command outputs the current active configuration as a series of 'set' commands, which can be directly copied and applied to another Junos device using 'load set terminal' or 'load merge'. This format is specifically designed for merging configurations, as it represents the configuration in a flat, non-hierarchical structure that Junos can parse incrementally.

Answer

show configuration | display inheritance

Answer

show configuration | display json

Answer

show configuration | save /var/tmp/config.txt

Question 15

Refer to the exhibit. An administrator wants to ensure that log messages are stored even if the remote syslog server becomes unavailable. What additional configuration is required?

Accepted Answer

set system syslog file messages any any. Configuring a local log file with `set system syslog file messages any any` ensures that log messages are stored locally on the device, even if the remote syslog server becomes unavailable. This provides a persistent local copy of logs that can be reviewed later, independent of the remote server's reachability.

Answer

set system syslog archive world-readable

Answer

set system syslog host 10.10.10.1 facility-override

Answer

set system syslog rate-limit 1000