JN0-106 Practice Test 20 — 15 Questions

Question 1

Order the steps to configure firewall filters (ACLs) in Junos.

Accepted Answer

First configure match conditions, then configure the action, and finally apply the filter to the interface.. Firewall filters are defined with terms (match conditions and actions) and applied to interfaces.

Answer

First apply the filter to the interface, then configure match conditions, then configure the action.

Answer

First configure the action, then configure match conditions, then apply the filter to the interface.

Answer

First configure match conditions, then apply the filter to the interface, then configure the action.

Question 2

A technician notices that the /var partition is filling up on a Juniper device. Which action would be most appropriate to free up space while preserving critical logs?

Accepted Answer

Run 'request system storage cleanup'. The 'request system storage cleanup' command is the correct action because it safely removes non-essential files such as old log files, core dumps, and temporary files that are no longer needed, while preserving critical logs and configuration files. This command performs a controlled cleanup without risking the deletion of important operational data, making it the most appropriate method for freeing up space on the /var partition.

Answer

Delete core files manually

Answer

Reboot the device

Answer

Delete all files in /var/log

Question 3

A company wants to implement best practice for password recovery on Juniper devices to avoid service disruption. Which of the following is the recommended method?

Accepted Answer

Boot the device into single-user mode from the console and reset the root password. Booting the device into single-user mode from the console is the standard, secure method for password recovery on Juniper devices. This process allows an administrator with physical console access to reset the root password without affecting the running configuration or causing service disruption, as the device boots with a minimal kernel and does not load the full configuration.

Answer

Perform a factory reset to default configuration

Answer

Use SNMP to modify the password field in the configuration

Answer

Contact JTAC to remotely reset the password

Question 4

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 5

A network engineer is designing a redundant network using RSTP. For faster convergence, what is the recommended method to avoid waiting for the forward delay timer?

Accepted Answer

Configure interfaces connected to end hosts as edge ports.. RSTP (Rapid Spanning Tree Protocol, IEEE 802.1w) achieves faster convergence by eliminating the listening and learning states for edge ports. Configuring interfaces connected to end hosts as edge ports allows them to transition directly to the forwarding state without waiting for the forward delay timer (default 15 seconds), because no BPDUs are expected on those ports and no loop can form.

Answer

Manually specify the root bridge and root port.

Answer

Use link aggregation to bundle multiple links.

Answer

Increase the hello timer to speed up BPDU exchange.

Question 6

A network engineer wants to view the OSPF log entries in real time. They type 'show log messages | match ospf' and get output, but it does not update. What should they do to see real-time updates of OSPF log entries?

Accepted Answer

Use 'monitor start messages | match ospf'. The 'monitor start messages' command in Junos OS enables real-time streaming of syslog messages to the terminal, similar to 'tail -f' on a log file. Piping the output through '| match ospf' filters the live feed to show only OSPF-related entries. In contrast, 'show log messages' is a one-time snapshot that does not update automatically.

Answer

Use 'show log messages | tail'

Answer

Use 'monitor traffic interface ge-0/0/0'

Answer

Use 'request system syslog'

Question 7

Refer to the exhibit. If the primary next-hop (192.168.1.1) becomes unreachable, what will happen to the route?

Accepted Answer

The secondary next-hop (192.168.2.1) will be used.. In Junos, when a route has multiple next-hops configured (e.g., primary and secondary), the secondary next-hop serves as a backup. If the primary next-hop (192.168.1.1) becomes unreachable, Junos automatically fails over to the secondary next-hop (192.168.2.1) without removing the route from the routing table. This behavior is controlled by the 'next-hop' configuration under a static route or via routing protocol policies, ensuring continuous reachability.

Answer

The route is removed from the routing table.

Answer

The route remains but with the primary next-hop marked as unreachable.

Answer

The route becomes hidden.

Question 8

During a maintenance window, an engineer makes critical changes and wants the configuration to automatically revert if they lose connectivity. Which command should they use before committing?

Accepted Answer

commit confirmed. 'commit confirmed', is correct because it allows the engineer to commit a configuration change with a default 10-minute rollback timer. If the engineer loses connectivity and does not confirm the commit within that period, the system automatically reverts to the previous configuration, ensuring the device remains reachable.

Answer

commit

Answer

commit check

Answer

commit at

Question 9

An engineer wants to roll back to the previous configuration. Which command should be used?

Accepted Answer

rollback 1. The `rollback 1` command loads the previous committed configuration (the configuration before the last commit) into the candidate configuration, discarding any uncommitted changes. This allows the engineer to replace the current candidate with the desired historical configuration. In Junos, `rollback 0` loads the most recently committed configuration (the current active configuration), not the previous one.

Answer

delete

Answer

rollback 0

Answer

commit check

Question 10

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 11

A network engineer needs to commit a configuration change but wants to ensure the change can be easily reverted if it causes issues. Which approach should the engineer take?

Accepted Answer

Use the 'commit confirmed' command with a timeout.. The 'commit confirmed' command allows the engineer to commit a configuration change with a default timeout of 10 minutes (configurable). If the change causes issues and the engineer does not confirm the commit within the timeout period, Junos automatically reverts to the previous active configuration, providing a safe rollback mechanism.

Answer

Use the 'commit and-quit' command to apply changes.

Answer

Use the 'commit check' command before committing.

Answer

Use the 'rollback 0' command after committing.

Question 12

A junior engineer uses 'set system host-name R1' in configuration mode and exits without committing. After a reboot, the hostname reverts to the original. What step did the engineer miss?

Accepted Answer

They must commit the configuration with 'commit'.. In Junos OS, configuration changes made in configuration mode are stored in a candidate configuration and do not take effect until explicitly committed using the 'commit' command. Rebooting without committing discards all uncommitted changes, causing the hostname to revert to its original value. Option D is correct because the engineer must issue 'commit' to activate the new hostname permanently.

Answer

They must use 'run set system host-name' instead.

Answer

They must save the configuration to a file.

Answer

They must reboot after setting the hostname.

Question 13

An organization has two ISPs and wants to load-balance traffic equally across both links for all outbound traffic. Which routing configuration approach should be used?

Accepted Answer

Configure two static default routes with equal metric values and enable ECMP.. Configuring two static default routes with equal metric values and enabling Equal-Cost Multi-Path (ECMP) allows the Juniper device to load-balance outbound traffic equally across both ISP links. ECMP uses per-flow or per-packet load balancing based on the hash of source/destination IP addresses and ports, ensuring traffic is distributed evenly without relying on dynamic routing protocols.

Answer

Configure two static default routes with different metric values.

Answer

Configure policy-based routing to match all traffic and forward to both ISPs.

Answer

Establish BGP sessions with both ISPs and rely on BGP path selection.

Question 14

Refer to the exhibit. The router has a default static route and a static route to 10.0.0.0/24. An engineer updates the next-hop for the default route from 192.168.1.1 to 192.168.1.2. Which command should the engineer use to verify that the change is active?

Accepted Answer

show route 0.0.0.0/0. The command 'show route 0.0.0.0/0' displays the routing table entry for the default route, including its next-hop address. After changing the next-hop from 192.168.1.1 to 192.168.1.2, this command confirms the active route has the updated next-hop. It directly verifies the specific prefix that was modified.

Answer

show route 192.168.1.2

Answer

ping 192.168.1.2

Answer

show route protocol static

Question 15

An engineer needs to load a full configuration from a text file onto a Junos device, replacing the entire candidate configuration. Which command should be used?

Accepted Answer

load override /path/to/config.txt. The 'load override' command replaces the entire candidate configuration with the contents of the specified text file, discarding any existing candidate changes. This is the correct choice because the engineer explicitly needs to replace the full configuration, not merge or patch it.

Answer

load set /path/to/config.txt

Answer

load patch /path/to/config.txt

Answer

load merge /path/to/config.txt