JN0-106 Junos Configuration Basics Practice Test 3 — 15 Questions

Question 1

Which THREE statements about commit options are true?

Accepted Answer

'commit confirmed' requires a second commit within the timeout to keep the changes.. Option B is correct because 'commit confirmed' applies the candidate configuration but automatically rolls back to the previous configuration unless a second commit is issued within the confirmation timeout (default 10 minutes), which is useful for preventing lockout. Option C is correct because 'commit synchronize' pushes and commits the configuration on both Routing Engines in a chassis cluster, keeping the primary and backup REs in sync. Option D is correct because 'commit check' performs a syntax and semantic validation of the candidate configuration without activating or committing it, allowing errors to be caught before a real commit. Option A is not correct because 'commit full' does not reinitialize the system; it forces a full commit that re-evaluates the entire configuration rather than only changed portions. Option E is not correct because 'commit and-quit' is not a valid Junos commit option; the correct behavior of committing and leaving configuration mode is achieved with 'commit' followed by 'exit', or 'commit and-quit' is not a recognized command in this context.

Answer

'commit full' reinitializes the system.

Answer

'commit and-quit' commits and exits configuration mode.

Question 2

Refer to the exhibit. What is the most likely cause of the error?

Accepted Answer

The policy-statement 'test' contains a syntax error in the protocol match condition.. The error message in the exhibit indicates a syntax error in the policy-statement 'test' when using the protocol match condition. In Junos, the 'protocol' match condition requires a valid protocol name (e.g., 'bgp', 'ospf', 'static'), and if an invalid or misspelled protocol is specified, the commit check fails with a syntax error. This is a common mistake when configuring policy-options, as the Junos CLI validates the protocol against a predefined list.

Answer

The IP address 1.1.1.1/32 is already in use.

Answer

The candidate configuration has no errors and this is a warning.

Answer

The commit check command requires user confirmation.

Question 3

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

Accepted Answer

load override. Options A and B are correct because Junos CLI provides the `load override` and `load merge` commands to load a configuration file (typically via `load override ` or `load merge `) into the candidate configuration. `load override` replaces the entire candidate configuration with the contents of the file, while `load merge` merges the file's configuration statements into the existing candidate configuration. Option C is not a valid Junos CLI command for loading a configuration file. Option D is incorrect because the actual Junos command is `load replace`, which is used to replace configuration objects marked with the `replace:` tag, but it is not one of the two standard methods asked for here and is not marked correct. Option E is incorrect because `load set` is not a valid Junos load command; set-style input is handled with `load set terminal` or by pasting set commands, not as a general file-load method.

Answer

import configuration

Answer

load replace

Answer

load set

Question 4

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. The 'read-only' class in Junos provides exactly the required permissions: the ability to view configuration and execute operational commands without any modification capabilities. The 'authentication plain-text-password' directive configures local password authentication, which meets the requirement for the junior engineer to authenticate using a local 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 5

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

Accepted Answer

commit synchronize. Option C, 'commit synchronize', is valid in Junos on dual Routing Engine platforms to commit the candidate configuration on both Routing Engines simultaneously and keep them in sync. Option D, 'commit confirmed 10', is valid because 'commit confirmed' activates the configuration but automatically rolls it back after the specified number of minutes (10 here) unless confirmed with another commit, which is useful for safe remote changes. Option E, 'commit check', is valid because it validates the candidate configuration for syntax and semantic errors without actually committing or activating it. Option A, 'commit full', is not a valid Junos commit option, and option B, 'commit no-sync', is not a valid Junos commit option either; the correct synchronization-related syntax is 'commit synchronize' (and 'commit no-synchronize' is not a standard commit option in this form).

Answer

commit full

Answer

commit no-sync

Question 6

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.. 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.

Question 7

A network engineer accidentally committed a configuration on a Juniper router that caused a loss of management access via SSH and SNMP. The engineer has console access and the device is still operational. Before the change, the engineer had saved a rescue configuration using 'request system configuration rescue save'. Which action should the engineer take to restore management access most quickly?

Accepted Answer

At the shell prompt, execute 'cli -c "rollback rescue"' and then commit.. The 'request system configuration rescue save' command stores a rescue configuration that can be rolled back to using 'rollback rescue' in configuration mode. Since the engineer has console access, they can enter configuration mode and execute 'rollback rescue' followed by 'commit' to instantly revert to the last known working configuration, restoring SSH and SNMP access without requiring a reboot.

Answer

At the configuration mode, execute 'rollback 0'.

Answer

Power cycle the device; it will automatically boot with the rescue configuration.

Answer

Reboot the device and press the space bar to load the rescue configuration.

Question 8

A Juniper router experiences a power outage. After power is restored, the router fails to boot completely and stops at the loader (U-Boot) prompt. You have console access. Before the outage, you had saved a rescue configuration. How can you load the rescue configuration to recover the system?

Accepted Answer

Type 'boot rescue' at the loader prompt.. At the U-Boot loader prompt, the 'boot rescue' command instructs the router to boot using the rescue configuration stored in the /config directory. The rescue configuration is a known-good configuration that can be saved via 'request system configuration rescue save' and is loaded directly by the boot loader when the normal boot process fails.

Answer

Type 'load rescue' at the loader prompt.

Answer

Power cycle with a pin in the reset hole.

Answer

Type 'boot -s' to enter single-user mode, then load rescue.

Question 9

A network administrator is configuring a Junos device and wants to ensure that a commit operation is successful. The administrator issues the commit command and receives an error indicating that the configuration check-out failed. Which two statements describe possible causes of this error? (Choose two.)

Accepted Answer

The user does not have permission to modify the candidate configuration.. A commit check-out failure occurs when the candidate configuration cannot be accessed or locked for the commit. This can happen if another user holds an exclusive lock on the candidate, or if the current user lacks permission to modify the candidate. Syntax errors and missing rollback files produce different error messages.

Answer

The commit operation was attempted without first entering configuration mode.

Answer

The rollback file is missing or corrupted.

Answer

The candidate configuration contains a syntax error that was not caught during editing.

Question 10

During troubleshooting, an engineer notices that BGP sessions are flapping. They suspect that the issue might be related to the maximum number of routes allowed. To see if the BGP import policy is rejecting routes, which operational command would provide immediate insight?

Accepted Answer

show bgp neighbor x.x.x.x. The 'show bgp neighbor x.x.x.x' command displays detailed BGP session information, including the number of received and accepted routes, as well as any prefix-limit or policy-related rejections. If the BGP import policy is rejecting routes due to exceeding the maximum allowed, this command will show the 'received prefixes' count alongside the 'accepted prefixes' count, immediately revealing if routes are being dropped. This provides direct insight into whether the flapping is caused by route limit enforcement.

Answer

show version

Answer

show interfaces terse

Answer

show route protocol bgp

Question 11

When configuring a new Juniper router, an engineer needs to ensure that configuration changes are not automatically committed after a certain time if not explicitly confirmed. Which configuration parameter controls this?

Accepted Answer

commit confirmed. The 'commit confirmed' command is used to apply a configuration change that will automatically roll back to the previous configuration if not explicitly confirmed within a specified time period (default 10 minutes). This ensures that changes are not permanently applied unless the engineer verifies them, preventing accidental lockout or misconfiguration.

Answer

commit check

Answer

commit at

Answer

commit synchronize

Question 12

An engineer is designing a network and needs to ensure that management traffic (SSH, SNMP) is always permitted, even if an interface firewall filter is applied. Which Juniper best practice should be followed?

Accepted Answer

Apply a firewall filter on the loopback interface (lo0) to protect the device. Applying a firewall filter to the loopback interface (lo0) is the Juniper best practice for protecting management traffic because the loopback interface is the logical termination point for all control plane traffic, including SSH and SNMP. This ensures that management traffic is always permitted regardless of which physical interface it arrives on, while still allowing interface-specific filters to be applied for data plane traffic without risk of blocking management access.

Answer

Use a firewall filter that permits all management traffic at the top of the list on each interface

Answer

Apply a firewall filter to the management interface (fxp0)

Answer

Disable the firewall filter on all interfaces

Question 13

A network engineer needs to add an additional IP address to an interface that already has a primary IP configured. Which method should be used?

Accepted Answer

set interfaces ge-0/0/0 unit 0 family inet address 10.0.0.2/24 secondary. In Junos, to add an additional IP address to an interface that already has a primary IP configured, you must append the 'secondary' keyword to the address configuration statement. This allows multiple IPv4 addresses on the same logical interface unit, with the first address assigned being the primary and subsequent addresses marked as secondary.

Answer

set interfaces ge-0/0/0 unit 0 family inet address 10.0.0.2/24

Answer

set interfaces ge-0/0/0 unit 0 family inet secondary address 10.0.0.2/24

Answer

set interfaces ge-0/0/0 unit 0 family inet address 10.0.0.2/24 primary

Question 14

Which THREE statements about the 'commit' command are correct?

Accepted Answer

The 'commit check' command validates the syntax of the candidate configuration.. Option A is correct because 'commit check' parses and validates the candidate configuration's syntax and semantics without actually activating it, so errors are reported before a real commit. Option B is correct because on a dual-RE (redundant Routing Engine) system, 'commit synchronize' commits the candidate configuration on both Routing Engines, keeping the primary and backup REs in sync. Option E is correct because 'commit confirmed 5' activates the configuration but automatically rolls back to the previous configuration after 5 minutes unless the administrator confirms it with a subsequent 'commit'. Option C is wrong because 'commit full' forces a full commit that re-evaluates the entire configuration and does perform validation, rather than skipping it. Option D is wrong because multiple users can be in configuration mode simultaneously; the 'commit' command is not restricted to a single user, though a commit lock may be used to prevent conflicting changes.

Answer

The 'commit full' command activates the configuration without performing any validation.

Answer

The 'commit' command can only be issued when no other users are in configuration mode.

Question 15

Refer to the exhibit. An engineer has made changes to the candidate configuration. What will happen when the engineer issues the 'commit' command?

Accepted Answer

Both the interface address and security policy will be activated.. In Junos, the 'commit' command activates all changes in the candidate configuration atomically. Both the interface address change and the security policy will be applied simultaneously after validation. Junos does not require a reboot for security policy changes, and syntax errors cause the commit to fail, not be ignored.

Answer

The commit will succeed but the security policy will be ignored due to a syntax error.

Answer

Only the interface address change will be committed because security policies require a reboot.

Answer

The configuration will be validated; if errors exist, the commit will fail.