JNCIA-JUNOS Junos Configuration Basics Practice Test 6 — 15 Questions

Question 1

A technician needs to load a new configuration file that replaces only the specific hierarchy paths present in the file, leaving all other existing configuration unchanged. Which load statement is appropriate?

Accepted Answer

load merge. The 'load merge' command is correct because it merges the contents of the specified configuration file with the current candidate configuration, adding or updating only the hierarchy paths present in the file while preserving all other existing configuration. This matches the requirement to replace only specific hierarchy paths without affecting the rest of the configuration.

Answer

load replace

Answer

load set

Answer

load override

Question 2

In a dual Routing Engine (RE) setup, an engineer commits a configuration change that should be applied to both REs synchronously. What is the correct command to ensure both REs receive the same configuration immediately?

Accepted Answer

commit synchronize. Option D is correct because the 'commit synchronize' command commits the configuration on the master Routing Engine and then automatically copies and commits the same configuration to the backup RE, ensuring both REs have identical active configurations immediately. This is the standard Junos method for synchronizing configurations in a dual-RE chassis.

Answer

commit confirmed

Answer

commit check synchronize

Answer

commit and-quit

Question 3

A network administrator needs to temporarily disable a set of configuration statements for testing without deleting them. Which approach should be used?

Accepted Answer

use the 'deactivate' command to mark the statements inactive. Option A is correct because the 'deactivate' command in Junos allows an administrator to temporarily disable a set of configuration statements without removing them from the configuration. When a statement is deactivated, it is prefixed with 'inactive:' in the configuration hierarchy, and the commit operation ignores it. This is ideal for testing changes, as the statements can be easily re-enabled using the 'activate' command.

Answer

delete the statements and later re-add from a backup

Answer

comment out the lines using #

Answer

set the configuration to a different group and remove apply-groups

Question 4

An administrator wants to view the differences between the current candidate configuration and the last committed configuration. Which command displays this?

Accepted Answer

show | compare. The 'show | compare' command displays the differences between the candidate and the active (committed) configuration.

Answer

show configuration

Answer

commit check

Answer

rollback ?

Question 5

A network engineer needs to restore the factory-default configuration on a Junos device. Which command sequence is correct?

Accepted Answer

load factory-default and then commit. The correct command sequence to restore factory-default configuration on a Junos device is 'load factory-default' followed by 'commit'. The 'load factory-default' command replaces the current candidate configuration with the factory-default configuration, but it does not take effect until a 'commit' is issued. This ensures the device reverts to its original settings without affecting the currently running configuration until explicitly committed.

Answer

set system host-name factory-default

Answer

request system zeroize

Answer

delete configuration and reboot

Question 6

Which TWO statements are true about the 'commit' operation in Junos?

Accepted Answer

The commit command validates the configuration syntax before applying it.. Option A is correct because the 'commit' command in Junos performs a full syntax and consistency validation of the candidate configuration before applying it. If any errors are detected, the commit is aborted and the candidate configuration remains unchanged, ensuring the active configuration is never corrupted.

Answer

The commit command automatically saves the configuration to a file on the hard disk.

Answer

After a commit, the candidate configuration is replaced with the active configuration.

Answer

A successful commit overwrites the rollback configurations.

Question 7

Which TWO of the following are valid methods to load a configuration file into a Junos device?

Accepted Answer

load override. Option A is correct because the 'load override' command replaces the entire candidate configuration with the contents of the specified configuration file, discarding any previous candidate changes. Option B is correct because 'load merge' combines the contents of the specified configuration file with the current candidate configuration, adding or updating statements without removing existing ones. Both are standard Junos CLI commands for loading configuration data.

Answer

import configuration

Answer

load replace

Answer

load set

Question 8

Which THREE of the following are characteristics of configuration groups in Junos?

Accepted Answer

The 'apply-groups' statement is used to specify which group(s) should be inherited.. Option A is correct because the 'apply-groups' statement is the Junos mechanism used to inherit configuration from a named configuration group. When you define a group under the 'groups' hierarchy, you then use 'apply-groups <group-name>' at the desired hierarchy level to pull that group's configuration into that location. This allows for modular and reusable configuration blocks.

Answer

A maximum of 10 groups can be applied to a single configuration statement.

Answer

Configuration groups do not allow individual statements within the group to be overridden in the main configuration.

Question 9

Scenario: Your company has a Juniper MX Series router at a branch office running Junos 18.4. The device has been in production for two years with a stable configuration. Yesterday, a senior engineer made several changes to the OSPF configuration to optimize routing for a new link. They committed the changes and left for the day. This morning, the branch office experiences intermittent connectivity, and the OSPF neighbor relationships are flapping. You suspect the recent OSPF changes caused the issue. You have remote console access to the router. The goal is to restore network stability as quickly as possible while preserving the ability to re-apply the changes after troubleshooting. Which course of action should you take?

Accepted Answer

Use 'rollback 1' to revert to the configuration before the changes, then 'commit confirmed 10' to verify stability.. Option C is correct because 'rollback 1' reverts the active configuration to the previous committed version (before the problematic OSPF changes), and 'commit confirmed 10' applies that rollback with a 10-minute confirmation timer. If connectivity stabilizes, the rollback becomes permanent; if not, the router automatically reverts to the previous configuration, ensuring no prolonged outage. This approach restores stability quickly while preserving the ability to later re-apply and test the OSPF changes in a controlled manner.

Answer

Use 'deactivate protocols ospf' to disable OSPF entirely and then manually re-enable pieces.

Answer

Immediately delete the OSPF configuration sections that were changed and re-add the original settings manually.

Answer

Perform a 'load factory-default' and 'commit' to reset the device to base settings, then reconfigure from backup.

Question 10

Scenario: Your company has a Juniper SRX300 firewall used as a branch gateway. It runs Junos 15.1X49. The firewall has multiple security policies, NAT rules, and VPN tunnels. Recently, you added a new security policy to allow traffic from the internal network to a specific public server. After committing, you notice that the firewall is logging repeated denials for traffic that should be matched by the new policy. The policy appears correctly configured in the candidate configuration. You want to verify that the policy is actually active and check for any hidden rules that might be causing the issue. Which of the following is the most effective first step to troubleshoot this problem?

Accepted Answer

Run 'show security policies detail' and examine the policy order to see if a previous policy is denying the traffic.. Option C is correct because the most common cause of traffic being denied despite a seemingly correct new policy is that a preceding policy in the security policy order matches the traffic and denies it before the new policy is evaluated. Junos security policies are evaluated in sequential order from top to bottom, and the first matching policy is applied. Running 'show security policies detail' displays the active policy order, including any hidden or default policies, allowing you to identify if a deny policy earlier in the list is intercepting the traffic.

Answer

Roll back to the previous configuration to ensure the device is in a known state.

Answer

Run 'show configuration | display set | match policy' to verify the policy is present.

Answer

Check the firewall logs with 'show log messages | match deny' to see which policy is denying.

Question 11

An engineer has modified the configuration and wants to apply changes but also wants to verify that the changes are syntactically correct before committing. What command should the engineer use?

Accepted Answer

commit check. The `commit check` command validates the candidate configuration for syntax errors without activating it. This allows the engineer to verify that the changes are syntactically correct before committing, ensuring the configuration is valid and reducing the risk of committing a broken configuration.

Answer

rollback

Answer

commit confirmed

Answer

commit

Question 12

A network administrator wants to configure a user account for a junior engineer. The junior engineer should only be able to view configuration and use operational commands, but not modify anything. Additionally, the junior engineer should be required to authenticate using a local password. Which configuration accomplishes this?

Accepted Answer

set system login user junior class read-only authentication plain-text-password. Option A is correct; it sets the user's class to 'read-only' with a password.

Answer

set system login user junior class operator authentication plain-text-password

Answer

set system login user junior class super-user authentication plain-text-password

Answer

set system login user junior class read-only authentication ssh-rsa

Question 13

Which TWO statements are true about the Junos configuration hierarchy?

Accepted Answer

The configuration is divided into a hierarchical tree.. The Junos configuration is organized as a hierarchical tree structure, where configuration statements are grouped under various hierarchy levels (e.g., 'system', 'interfaces', 'protocols'). Each statement in this tree is terminated by a semicolon, which is a fundamental syntax rule inherited from the Junos OS CLI. This hierarchical model allows for modular, structured configuration management.

Answer

Configuration is organized into two main hierarchies: system and interfaces.

Answer

Configuration must be entered in a specific order.

Answer

It is a flat structure with no grouping.

Question 14

Which THREE of the following are valid commit options in Junos?

Accepted Answer

commit synchronize. Option C is correct because 'commit synchronize' is a valid Junos commit option used on a dual Routing Engine (RE) system to apply the configuration changes to both REs simultaneously, ensuring configuration consistency across the chassis. This command is essential for high-availability setups where both REs must share the same active configuration.

Answer

commit full

Answer

commit no-sync

Question 15

You are a junior network engineer tasked with configuring a Juniper device for the first time. The device has just been powered on and you have console access. The device boots normally and shows the login prompt. There is no root password configured, but when you try to log in as root, you are prompted for a password. You do not have any previous configuration access. What should you do to gain access and begin configuring the device?

Accepted Answer

Press the space bar during boot, then type 'boot -s' at the loader prompt.. Option B is correct because when a Juniper device has no root password set, the default behavior is to require a password at the login prompt, even if none was configured. To bypass this, you must interrupt the normal boot process by pressing the space bar during the boot sequence, then at the loader prompt type 'boot -s' to boot into single-user mode. Single-user mode grants root access without a password, allowing you to set a root password and proceed with configuration.

Answer

Contact support to obtain a password reset.

Answer

Use the default login root with no password by pressing Enter.

Answer

Press Ctrl+C during boot to enter recovery mode.