Practice with JN0-106 Dumps for JNCIA Certified Exam Questions & Answer [Q128-Q146]

August 15, 2026August 15, 2026 examdumpsPractice with JN0-106 Dumps for JNCIA Certified Exam Questions & Answer [Q128-Q146] 0 Comment

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Practice with JN0-106 Dumps for JNCIA Certified Exam Questions & Answer

REAL JN0-106 Exam Questions With 100% Refund Guarantee

Juniper JN0-106 Exam Syllabus Topics:

Topic	Details
Topic 1	Junos OS Fundamentals: Covers the architecture of Junos OS, focusing on the separation of control and forwarding planes and how traffic is processed by the routing and packet-forwarding engines.
Topic 2	Operational Monitoring and Maintenance: Covers the tools and procedures used to monitor, maintain, and troubleshoot Junos devices, including show monitor commands, network utilities, OS upgrades, and password recovery.
Topic 3	Routing Fundamentals: Covers core routing concepts on Junos devices, including routing and forwarding tables, route preference, static routing, routing instances, and an introduction to dynamic routing protocols.
Topic 4	User Interfaces: Covers how to navigate and use the Junos CLI and J-Web interface, including configuration management, output filtering, and working with active versus candidate configurations.
Topic 5	Networking Fundamentals: Covers core networking concepts including IP addressing, subnetting, Layer 2 3 operations, routing basics, and protocol types essential for understanding how networks function.

Q128. Which Junos feature limits the amount of exception traffic that is sent from the PFE to the RE?

scheduler

routing policy

CoS markings

policer

Q129. You must add a large hierarchical configuration to your Junos device. You also want to completely replace the existing candidate configuration with a new configuration file. Which command would allow you to accomplish these tasks?

load merge terminal

load override terminal

load factory default

load set terminal

The load override terminal command replaces the entire candidate configuration with the new configuration being entered, making it suitable for loading a large hierarchical configuration and discarding the existing one.

Q130. Which criteria does the Junos OS use to select an active route when two entries exist in the routing table?

the route with the lowest preference number

the most recently learned dynamic route

the route with the highest preference number

the route with the highest metric

In Junos OS, when two entries for the same destination exist in the routing table, the route with the lowest preference number is selected as the active route. This preference number, also known as the route preference or administrative distance, is used to prioritize routes received from different routing protocols.

Q131. Which statement accurately describes the purpose of route preference in Junos OS?

It sets the metric for forwarding traffic through the Packet Forwarding Engine.

It determines which route is selected as active when multiple routes to the same destination exist.

It controls the redistribution of routes between routing instances.

It determines the maximum number of routes that can be installed in the routing table.

In the Junos OS architecture, the routing table often receives prefix information from various sources, including direct connections, static configurations, and multiple dynamic interior and exterior gateway protocols. Route preference, frequently referred to as administrative distance in other vendor environments, serves as the primary tie-breaking mechanism used by the Routing Engine to select a single ” active ” route when multiple entries for the exact same destination prefix exist from different protocol sources. Each routing source is assigned a default numerical value, where a lower numerical value indicates a more preferred or ” trustworthy ” source. For instance, a direct route typically carries a preference of 0, while OSPF internal routes default to 10 and BGP routes default to 170.
The selection process evaluates these values; the route with the lowest preference is installed in the forwarding table and used for transit traffic. If preferences are equal, Junos secondary tie-breakers like local preference or metric are considered. Understanding this hierarchy is critical for traffic engineering and ensuring predictable routing behavior across the fabric. Modification of these default values via routing policy allows administrators to influence path selection without altering the underlying protocol metrics themselves.
Reference: Routing Fundamentals, Route Preference Selection.

Q132. Which character is used to filter the command output in the Junos CLI?

In the Junos CLI, the pipe character | is used as a filter operator to refine command output. This operator can be combined with various filtering commands like match, except, count, etc., to display only the relevant portions of the command output. For example, using | match <pattern> filters the output to show only the lines that contain the specified pattern, making it easier to find specific information within extensive command output. This functionality is especially useful in managing and troubleshooting complex configurations and network states, allowing for more efficient analysis of the device’s operational status and configuration details.

Q133. You are using the factory default configuration on a new Juniper router. You must successfully commit the configuration and activate the device. Which component must be configured before Junos OS will allow you to accomplish this task?

a system hostname

a root-authentication password

at least one logical interface with family inet enabled

a management IP address on the fxp0 interface

When a Junos device is initialized for the first time or after a factory reset, it operates with a ” factory-default
” configuration. This configuration contains the minimum settings necessary for the device to boot, but it lacks essential security parameters. The Junos OS kernel enforces a strict security mechanism that prevents any administrator from successfully executing a commit command until a root-level password has been defined.
Specifically, the root-authentication object must be configured under the [edit system] hierarchy. This requirement ensures that no Junos device is deployed into a production environment with an open, unauthenticated root account. If an administrator attempts to commit changes without this setting, the configuration parser will return a ” missing mandatory statement ” error and the commit process will fail.
While other settings-such as a system hostname, management IP address (on the fxp0 or me0 interfaces), or logical interface configurations-are critical for operational readiness, they are not strictly enforced by the system validation logic for the initial activation. Only the root-authentication (which can be a plain-text password or an encrypted key) is a hard prerequisite for transitioning the device from a default state to an active, running configuration.
Reference: Configuration Basics, Initial Configuration, System Security.

Q134. You must view the forwarding table on your Junos device to troubleshoot a packet forwarding issue. In this scenario, which command would display the forwarding table?

show route table

show route forwarding-table

show ip forwarding

show forwarding-options

To effectively troubleshoot packet forwarding in a Junos environment, an architect must distinguish between the control plane ‘ s Routing Information Base (RIB) and the data plane ‘ s Forwarding Information Base (FIB). While the command show route displays the RIB (the master routing table maintained by the Routing Engine), it does not necessarily reflect the actual instructions being executed by the hardware. The definitive command for viewing the data plane ‘ s active path selection is show route forwarding-table.
Executing this command reveals the contents of the FIB as it has been pushed from the Routing Engine to the Packet Forwarding Engine (PFE). The output provides critical diagnostic data, including the destination prefix, the specific next-hop IP address, the interface through which the packet will egress, and the type of route (such as unicast or broadcast). This is the ” ground truth ” for packet movement; if a route exists in the RIB but is missing from the forwarding table, it indicates a failure in the communication between the RE and PFE. Utilizing this command is the primary method for identifying black holes, incorrect next-hop resolution, or issues with hardware-level filter applications that might be impacting transit traffic flow at wire speed.
Reference: Routing Fundamentals, Forwarding Information Base (FIB), Troubleshooting Forwarding.

Q135. Which protocol provides secure remote CLI access to a Junos device?

FTP

SNMP

Telnet

SSH

Securing the management plane is a core requirement for any Junos OS deployment. Secure Shell (SSH) is the industry-standard protocol used to provide encrypted, authenticated remote access to the Junos Command Line Interface (CLI). Unlike Telnet, which transmits both administrative credentials and command data in cleartext, SSH utilizes public-key cryptography to establish a secure tunnel, protecting the session from eavesdropping, man-in-the-middle attacks, and unauthorized interception.
In Junos OS, SSH is typically enabled within the [edit system services] hierarchy. Once active, it allows administrators to perform operational and configuration tasks with the assurance that their management traffic remains confidential. Beyond simple terminal access, SSH serves as the transport mechanism for other secure management functions, such as the NETCONF XML management protocol and Secure Copy (SCP) for file transfers. For high-security environments, Junos supports advanced SSH features including key-based authentication, strong cipher suites, and multi-factor authentication integration. Disabling insecure protocols like Telnet and FTP in favor of SSH and SFTP/SCP is a foundational best practice for hardening the Routing Engine against external threats.
Reference: User Interfaces, Accessing the Junos CLI, System Services.

Q136. You committed a new configuration on a Junos router, but users report connectivity issues. You must quickly restore the previous working configuration without manually editing the candidate configuration. Which command should you use to load the required configuration into the candidate configuration?

rollback 0

show | compare rollback

rollback 1

load override

In Junos OS, the configuration database is designed with a robust versioning system that facilitates rapid recovery from administrative errors. Every time a commit command is successfully executed, the system automatically archives the previous active configuration and assigns it a ” rollback ” index. The rollback command is used within configuration mode to revert the candidate configuration to a previously saved state.
The indices are zero-based, where rollback 0 represents the currently active configuration that was just committed. To restore the configuration that was functional immediately before the most recent, problematic commit, the administrator must use rollback 1. This command replaces the current candidate configuration with the contents of the last known working state. It is important to note that executing rollback 1 only populates the candidate buffer; to make this previous configuration active and restore connectivity, the administrator must subsequently issue the commit command. This mechanism is a cornerstone of Junos OS ‘ s commitment to high availability and operational resilience, allowing for nearly instantaneous restoration of services without the need for manual line-by-line configuration edits during a network outage.
Reference: Configuration Basics, Managing Configurations, Rollback configurations.

Q137. What are two attributes of the UDP protocol? (Choose two.)

UDP is more reliable than TCP.

UDP is always slower than TCP.

UDP is best effort.

UDP is connectionless.

UDP (User Datagram Protocol) is known for being connectionless (D) and providing best-effort delivery without the reliability mechanisms present in TCP (C). This means that UDP does not establish a connection before sending data and does not guarantee delivery, order, or error checking, making it faster but less reliable than TCP.

Q138. Which two statements are correct about Junos OS? (Choose two.)

Junos OS provides the ability to run unsigned third-party binaries.

Junos OS provides modularization of software processes.

Junos OS combines security and routing policies.

Junos OS separates the control plane and the forwarding plane.

Junos OS is built upon a highly stable and secure architecture that distinguishes it from many legacy network operating systems. Two of its most defining characteristics are software modularization and the separation of the control and forwarding planes .
Modularization means that Junos OS runs each major function-such as the routing protocol process (rpd), the management process (mgd), and the interface process (dcd)-as an independent software daemon in its own protected memory space. This ensures that if a single process crashes or needs to be restarted, it does not bring down the entire system or interrupt traffic forwarding.
Furthermore, the physical and logical separation of the Control Plane (Routing Engine) and the Forwarding Plane (Packet Forwarding Engine) is a cornerstone of Junos design. The Routing Engine handles complex intelligence, protocol calculations, and management, while the Packet Forwarding Engine performs high- speed packet switching in hardware. This ensures that a heavy management load or a complex routing recalculation won ‘ t cause ” jitter ” or packet loss for transit traffic. Conversely, Junos strictly prohibits unsigned third-party binaries to maintain system integrity, and it maintains a clear functional distinction between routing policies (path selection) and security policies (traffic permit/deny).

Q139. You want to find out the chassis serial number of a Junos device. Which command would display this information?

show chassis environment

show chassis hardware

show chassis routing-engine

show chassis location

The show chassis hardware command in Junos OS displays detailed information about the hardware installed in the device, including the chassis itself. This command provides a list of all hardware components, their serial numbers, part numbers, and version information. When looking for the chassis serial number specifically, this command is the most direct and comprehensive way to retrieve that information, as it includes the serial number of the chassis among the details provided.

Q140. What is the purpose of the Address Resolution Protocol (ARP)?

to map IPv4 addresses to MAC addresses

to perform next-hop IP address resolution for newly learned routes

to perform routing policy processing for newly learned routes

to distribute IPv6 addresses

The purpose of ARP is to resolve or map IPv4 addresses to their corresponding MAC (hardware) addresses, allowing devices to communicate over Ethernet networks.

Q141. Which two tasks would you perform in operational mode? (Choose two.)

requesting the system to reboot

verifying the version of Junos OS

committing your configuration

rolling back to a previous configuration

The Junos Command Line Interface (CLI) is structured into two primary hierarchical modes:
operational mode and configuration mode. Operational mode is the default entry point when a user logs into the device, signified by the > prompt. This mode is designed for monitoring the health of the device, troubleshooting network issues, and executing system-level maintenance tasks. Specifically, an administrator uses operational mode to verify the version of Junos OS currently active on the device using the show version command.
Additionally, system-level administrative actions that do not involve modifying the device’s persistent configuration logic are performed within the operational mode. This includes requesting the system to reboot or halt via the request system hierarchy of commands. In contrast, tasks that involve manipulating the configuration database–such as committing proposed changes or rolling back to a previous configuration version–require the user to transition into configuration mode, indicated by the # prompt. Understanding this distinction is vital for efficient navigation of the Junos CLI; while operational mode provides the tools to observe the system and manage its physical state, configuration mode is reserved for altering the logical parameters and routing policies that govern device behavior.

Q142. Which protocol connects multiple autonomous systems?

OSPF

IS-IS

IBGP

EBGP

BGP (Border Gateway Protocol) is the standard exterior gateway protocol used to exchange routing information between different autonomous systems (ASes), enabling communication across the internet backbone.
– iBGP (Internal BGP) is used for routing within a single AS.
– eBGP (External BGP) is used to connect and exchange routing information between multiple autonomous systems.

Q143. How many rescue configuration files are supported on a Junos device?

Junos OS supports only 1 rescue configuration file on a device. This rescue configuration is a safeguard feature that allows network administrators to revert to a known good configuration in case of a configuration error or issue, ensuring network stability.

Q144. Which two statements correctly describe how Junos OS handles control and forwarding functions? (Choose two.)

The Packet Forwarding Engine (PFE) forwards packets based on forwarding tables received from the Routing Engine.

Exception traffic is always dropped by the Packet Forwarding Engine without being inspected.

Transit traffic is processed by the Routing Engine to ensure high-speed packet forwarding.

The Routing Engine (RE) is responsible for maintaining routing tables and running routing protocols.

The Packet Forwarding Engine uses forwarding tables provided by the Routing Engine to forward traffic efficiently. The Routing Engine maintains routing tables and runs routing protocols as part of control plane operations.

Q145. Which command allows you to commit a configuration and automatically roll it back if you do not confirm the commit within a specified time?

commit check

commit confirmed

commit synchronize

commit at

The commit confirmed command commits the configuration temporarily; if a subsequent commit is not issued within the specified timeframe (default 10 minutes), the device automatically reverts to the previous configuration, which helps prevent lockouts from bad configurations.

Q146. Which two addresses are included in an Ethernet frame header? (Choose two.)

source IP address

source MAC address

destination IP address

destination MAC address

An Ethernet frame header includes the source MAC address (B) and the destination MAC address (D). These addresses are used to deliver the frame from one Ethernet device to another directly connected Ethernet device on the same network segment. Ethernet frames do not include IP addresses, as those are part of the IP packet encapsulated within the Ethernet frame.

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