Free and Premium Juniper JN0-105 Dumps Questions Answers

The Packet Forwarding Engine (PFE) is an integral component of Juniper Networks devices, responsible for the data plane operations. The data plane, also known as the forwarding plane, is where the actual processing and forwarding of packets occur based on the routing and forwarding tables. The PFE executes the forwarding decisions made by the Routing Engine (RE), handling all packet transmissions, including routing, filtering, and switching packets towards their destination. This contrasts with the control plane operations handled by the RE, which involve routing table maintenance, system management, and control protocol processing.

If you've committed a configuration and then need to revert to the previous configuration, the rollback command is used. Since the incorrect IP address has not been committed, as indicated by the commit check command being successful, issuing rollback 1 will undo the changes made in the current session, which includes the accidental entry of the IP address.

In Junos OS, a policer is a feature used to limit the rate of traffic flow in the network, including exception traffic sent from the Packet Forwarding Engine (PFE) to the Routing Engine (RE). Exception traffic consists of packets that cannot be processed by the PFE alone and require intervention by the RE, such as control packets or packets destined for the device itself. A policer can be configured to enforce bandwidth limits and drop or mark packets that exceed specified rate limits, thus protecting the RE from being overwhelmed by excessive exception traffic.

In Junos OS, route preference (also known as administrative distance) is used to determine the preferred route among multiple routes to the same destination learned via different routing protocols. Direct and local routes, which represent directly connected networks and interfaces, typically share the same low preference value, indicating high trustworthiness because they are directly connected to the router. OSPF internal routes (routes within the same OSPF area) and OSPF AS external routes (routes that are external to the OSPF autonomous system but redistributed into OSPF) also share the same preference value, although this value is higher (indicating less trust) than for direct and local routes. This distinction helps the routing engine decide which routes to use when multiple paths are available.

In Junos OS, the management daemon (mgd) is responsible for handling all the device management tasks, including processing CLI commands and handling commit operations. The mgd daemon interacts with the Junos OS configuration database and provides the necessary logic to ensure that configuration changes are syntactically correct and do not conflict with each other. When a user commits a configuration, mgd validates the changes, applies them to the running configuration, and ensures that the necessary daemons are notified of the changes to apply them accordingly.

In Junos OS, the # prompt indicates that you are in configuration mode. This mode is used for making changes to the configuration of the device.

The CLI help command in Junos OS provides assistance and explanations for commands, command options, and in some cases, specific system log error messages. By using the help command followed by specific keywords or messages, users can get detailed information and context for the commands they are using or errors they are encountering. This feature is particularly useful for understanding the purpose of commands, their syntax, and troubleshooting error messages that may appear in system logs.

The show | compare command in Junos OS is used to display the differences between the candidate configuration and the active configuration. If no output is shown when you issue this command, it means that there are no changes between the candidate configuration and the active configuration. This indicates that the candidate configuration is identical to the active configuration, and thus no differences are displayed.

In Junos OS, to navigate from operational mode to configuration mode, you can use either the edit or configure command. Both commands move the CLI from operational mode, where you can view the state of the device, to configuration mode, where you can make changes to the device's configuration.

In the Junos OS, multiple software processes run independently in their own protected memory spaces. This design ensures that if one process crashes or encounters an issue, it does not affect the other processes running on the system. This architecture enhances the stability and reliability of the network device, as each process operates independently and securely.

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.

Referring to the exhibit, the presence of the "+" symbol next to the OSPF route for 192.168.100.2/32 indicates that this is the active route being used to forward traffic. The BGP route, although present, does not have the "+" symbol, indicating it is not the active route. In Junos OS, the routing table displays the active route with a "+" symbol, and the fact that the OSPF route has this symbol means it is the preferred path based on the routing protocol's decision process, which takes into account factors such as route preference (administrative distance) and metrics.

MAC (Media Access Control) addresses are unique identifiers assigned to network interfaces for communications at the data link layer of a network segment. MAC addresses are used to identify the physical hardware on a network. In the context of Ethernet switches, the destination MAC address in incoming frames is used to determine the appropriate output port for forwarding the frame towards its final destination. The switch does not change the destination MAC address; it uses the MAC address to make forwarding decisions within the local network segment.

In Junos OS, the dedicated out-of-band management interface is typically named fxp0. This interface is used exclusively for management traffic and is physically separated from the data traffic interfaces. It allows administrators to perform management tasks even when the device is experiencing issues that affect the forwarding plane.

From the JNCIA-Junos Study Guide and Junos OS Documentation:

“The fxp0 interface is a dedicated management interface that provides out-of-band management access. It is commonly found on Juniper routers, switches, and security platforms. You assign IP addresses to this interface as you would any other, and it is often used to connect to a management network or to allow SSH, Telnet, or SNMP access.”

— Junos OS Fundamentals, Chapter: Interfaces

— Junos OS Documentation: Management Interfaces Overview

— JNCIA-Junos Exam Objective: Interface Types

The Routing Engine (RE) in Juniper Networks devices plays a critical role in the control plane operations. One of its functions includes responding to network utility commands like ping and traceroute, which are essential for diagnosing network connectivity and path issues. Furthermore, the RE is responsible for maintaining the routing tables, which contain information about network paths and destinations. These tables are vital for making forwarding decisions but are distinct from the actual forwarding of packets, which is handled by the Packet Forwarding Engine (PFE).

In Junos OS routing policy evaluation, "next policy" (A) and "next term" (C) are common actions that affect the flow of policy evaluation. "Next policy" directs the evaluation to the next policy in the sequence, whereas "next term" moves the evaluation to the next term within the current policy, allowing for granular control over routing decisions.

The transport layer in the OSI model is responsible for end-to-end communication and error recovery. In a transport header, such as TCP or UDP, the key components include the source port number and the destination port number. These port numbers are used to identify sending and receiving applications. The source port number indicates the port of the sending application, and the destination port number refers to the port of the receiving application. MAC addresses, on the other hand, are part of the data link layer (Layer 2) and would be included in an Ethernet header, not a transport header.

The Routing Engine (RE) in Juniper Networks devices plays a pivotal role in the control plane, handling tasks that are critical for the operation and management of the network. One of its key functions is processing management traffic, which includes user commands, system configuration, and monitoring operations. The RE also maintains routing tables, which are essential for network routing decisions. These tables contain network topology information and routing paths, which the RE uses to update the Packet Forwarding Engine (PFE) so that it can forward packets appropriately. The RE does not forward transit traffic or process Class of Service (CoS) marked traffic, as these tasks are handled by the PFE.

In the Junos OS command-line interface (CLI), the keyboard shortcut Ctrl+a is used to move the cursor to the start of the line. This is a common convention in many command-line environments and text editors, providing a quick way to navigate to the beginning of the current command or line of text without having to use the arrow keys. This can be particularly useful for making quick edits to commands or for navigating long lines of text more efficiently.

To view real-time usage statistics for the busiest interfaces on a device running Junos OS, the correct command is B, "monitor interface traffic." This command provides a dynamic, real-time view of the traffic flowing through the interfaces, allowing administrators to quickly identify and monitor the busiest interfaces on the device.

When creating a new policy to accept and redistribute routes into your Interior Gateway Protocol (IGP), the route-filter match criteria is used to identify the route prefixes to select. The route-filter statement specifies which prefixes should be matched in a policy. This allows for precise control over which routes are accepted and redistributed, facilitating efficient and secure routing policies within the network.

Implementing Class of Service (CoS) in a network provides numerous benefits, particularly in managing traffic based on its importance, source, or type. CoS enables network administrators to manage traffic congestion by applying various queuing techniques and policies to ensure that critical services remain unaffected during high congestion periods. Additionally, CoS allows for the prioritization of latency-sensitive traffic such as voice and video, ensuring that these services maintain quality despite varying network conditions.

In the OSI model, the Data Link Layer is responsible for node-to-node delivery of data. It frames the packets received from the Network Layer and prepares them for physical transmission. The Protocol Data Unit (PDU) for the Data Link Layer is called a "frame." Frames encapsulate the network layer packets, adding a header and a trailer that include the hardware addresses of the source and destination, among other things, facilitating the data link layer services like frame synchronization, flow control, and error checking.

The Network Time Protocol (NTP) is designed to synchronize the clocks of computers over a network. Configuring NTP on a Junos device ensures that its clock is set accurately, which is crucial for logging, troubleshooting, and maintaining the integrity of time-sensitive operations and security protocols. NTP allows devices to use a hierarchy of time sources, from primary servers synchronized to a reference clock (such as an atomic clock or GPS time) to secondary servers that distribute the time to other devices on the network.

The Packet Forwarding Engine (PFE) in Junos OS performs several key functions, including implementing firewall filters (A) and forwarding transit traffic (C). The PFE applies firewall filter rules to incoming and outgoing traffic and is responsible for the high-speed forwarding of packets based on the information in the forwarding table.

At the operational mode prompt on a Junos device, you can use various commands to view the device's status and request system operations. The show interface ge-0/0/0 command is used to display information about a specific interface, while the request system shutdown command is used to properly shut down the device. The set command is used in configuration mode, not operational mode, and the run command is used to execute operational mode commands from configuration mode.

Firewall filters in Junos OS are stateless, meaning they process each packet individually without regard to the state of a connection or sequence of packets. These filters can match various packet attributes, including those at Layer 4, such as TCP and UDP port numbers. This allows for granular control over traffic based on the type of service or application. Unlike stateless filters, stateful firewalls keep track of the state of active connections and make decisions based on the context of the traffic flow, which is not a capability of Junos firewall filters. Additionally, Junos firewall filters primarily operate up to Layer 4 and do not natively inspect Layer 7 parameters, which involve application-level data.

In Juniper firewall filter configurations, "discard" and "accept" are two valid terminating actions for a term within a filter. The "discard" action drops the packet, preventing it from reaching its intended destination, while the "accept" action allows the packet to pass through the filter, proceeding to its next hop or destination. "Count" is a non-terminating action that increments a counter every time a packet matches the term but does not inherently determine the packet's fate. "Next term" directs the evaluation to proceed to the next term in the filter for further processing, also a non-terminating action.

The routing table and forwarding table play distinct roles in a Junos OS device. The correct answers are A and D. The routing table (A) is used by the Routing Engine (RE) to select the best route among all the learned routes, while the routing table (D) stores all routes and prefixes learned from all routing protocols. The forwarding table, in contrast, contains only the active routes chosen by the RE and is used by the Packet Forwarding Engine for actual packet forwarding.

In the scenario where the system authentication order is set to "tacplus radius password," the correct statement is (B). If the TACACS+ and RADIUS servers are unreachable or fail to respond, the system will fall back to using password authentication. This ensures that users can still authenticate using locally stored passwords if external authentication servers are unavailable.

The exhibit shows a ping test being executed from router R2 to the IP address 10.23.0.3. Since the ping command is issued on R2 and we see successful replies from 10.23.0.3, it means the source of the ping must be an interface on R2. Given the network diagram and the IP address scheme, the source IP address of the ping is on the interface ge-0/0/2 of R2, which is in the subnet 10.23.0.0/24. The only logical IP address for R2's interface in this subnet, based on standard networking practices and the given options, would be 10.23.0.2. The other addresses provided in the options belong to different subnets or are the destination of the ping itself.

The firewall filter configuration in the exhibit specifies a filter with two terms. Term 1 matches traffic from the source address 10.0.0.0/8 and has two actions: 'log' and 'next term'. The 'log' action will record the match to a log file, and 'next term' indicates that the firewall should evaluate the next term after logging. There is no explicit action such as 'accept' or 'reject' in term 1, so by default, the traffic will be accepted unless subsequently rejected by another term.

Term 2 has the action 'reject', which discards packets that reach this term. Since there is no 'from' condition in term 2, it acts as a default rule for all traffic not matched by term 1.

Because the traffic sourced from 10.0.0.0/8 matches term 1 and there is no reject action in that term, it will be logged and then accepted by the firewall filter. There is no subsequent term that rejects this specific traffic, so the action from term 2 does not apply to it.