Practice Free JN0-105 Exam Online Questions
Question #11
Which two statements about route preference in Junos are correct? (Choose two.)
- A . Both direct and static routes have the same preference.
- B . Both direct and local routes have the same preference.
- C . Both OSPF internal and OSPF AS external routes have the same preference.
- D . Both EBGP and IBGP routes have the same preference.
Correct Answer: B, C
B, C
Explanation:
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.
B, C
Explanation:
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.
Question #12
Which component is considered part of the data plane?
- A . the Routing Engine
- B . the Packet Forwarding Engine
- C . the power supply
- D . the fan tray
Correct Answer: B
B
Explanation:
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.
B
Explanation:
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.
Question #13
You received a new Junos device and are configuring the system-related settings. You must configure this device for the current date and time on the US West coast. You have set the time zone to America/Los_Angeies. however the time and date did not change.
In this scenario, which two additional actions would satisfy this requirement? (Choose two.)
- A . Set the date and time setting manually.
- B . Configure an NTP server.
- C . Configure a DNS server.
- D . Reboot the device.
Correct Answer: A, B
A, B
Explanation:
When configuring the system-related settings for the current date and time on a Junos device, especially for a specific time zone like America/Los_Angeles, and the time does not automatically adjust, two effective actions can be taken. Firstly, setting the date and time manually allows for immediate correction of the system clock. This can be done via the CLI with the appropriate set date and time command. Secondly, configuring the device to use an NTP server can provide ongoing synchronization with an accurate time source, ensuring that the device maintains the correct time and date automatically in the future, even in the case of restarts or minor drifts in the internal clock.
A, B
Explanation:
When configuring the system-related settings for the current date and time on a Junos device, especially for a specific time zone like America/Los_Angeles, and the time does not automatically adjust, two effective actions can be taken. Firstly, setting the date and time manually allows for immediate correction of the system clock. This can be done via the CLI with the appropriate set date and time command. Secondly, configuring the device to use an NTP server can provide ongoing synchronization with an accurate time source, ensuring that the device maintains the correct time and date automatically in the future, even in the case of restarts or minor drifts in the internal clock.
Question #14
Which two statements about firewall filters are correct? (Choose two.)
- A . Firewall filters are stateless.
- B . Firewall filters can match Layer 7 parameters.
- C . Firewall filters are stateful.
- D . Firewall filters can match Layer 4 parameters.
Correct Answer: AD
AD
Explanation:
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.
AD
Explanation:
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.
Question #15
What information is exchanged during a TCP three-way handshake? (Choose two)
- A . port numbers
- B . interfaces
- C . sequence numbers
- D . application name
Correct Answer: A, C
A, C
Explanation:
The TCP three-way handshake establishes a reliable connection between two hosts. During this process:
SYN: The client sends a TCP segment with the SYN flag set, including an initial sequence number (ISN) and port information.
SYN-ACK: The server responds with a SYN-ACK, which contains its own sequence number and acknowledgment of the client’s ISN.
ACK: The client replies with an ACK, confirming receipt of the server’s ISN.
Thus, port numbers (to identify the application endpoints) and sequence numbers (to ensure ordered and reliable data transfer) are exchanged.
Interfaces and application names are not exchanged during this process.
From Junos OS Fundamentals / TCP Concepts:
“The TCP three-way handshake establishes a reliable session by exchanging port numbers and sequence numbers between peers. This process synchronizes both sides before data transmission begins.”
Reference: Juniper TechLibrary C TCP Overview
JNCIA-Junos Exam Objective: TCP/IP Concepts
A, C
Explanation:
The TCP three-way handshake establishes a reliable connection between two hosts. During this process:
SYN: The client sends a TCP segment with the SYN flag set, including an initial sequence number (ISN) and port information.
SYN-ACK: The server responds with a SYN-ACK, which contains its own sequence number and acknowledgment of the client’s ISN.
ACK: The client replies with an ACK, confirming receipt of the server’s ISN.
Thus, port numbers (to identify the application endpoints) and sequence numbers (to ensure ordered and reliable data transfer) are exchanged.
Interfaces and application names are not exchanged during this process.
From Junos OS Fundamentals / TCP Concepts:
“The TCP three-way handshake establishes a reliable session by exchanging port numbers and sequence numbers between peers. This process synchronizes both sides before data transmission begins.”
Reference: Juniper TechLibrary C TCP Overview
JNCIA-Junos Exam Objective: TCP/IP Concepts
Question #16
How many rescue configuration files are supported on a Junos device?
- A . 50
- B . 3
- C . 1
- D . 49
Correct Answer: C
C
Explanation:
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.
In Junos OS, each device supports only one rescue configuration file. The rescue configuration is a specific configuration that can be saved and later retrieved if needed. This is used as a fallback configuration that you know works and can be applied in case of an emergency or if the current configuration has issues.
Reference: Juniper Networks Documentation on Rescue Configuration
"You can create a rescue configuration file by using the request system configuration rescue save operational mode command. Each Junos OS device can have only one rescue configuration file."
C
Explanation:
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.
In Junos OS, each device supports only one rescue configuration file. The rescue configuration is a specific configuration that can be saved and later retrieved if needed. This is used as a fallback configuration that you know works and can be applied in case of an emergency or if the current configuration has issues.
Reference: Juniper Networks Documentation on Rescue Configuration
"You can create a rescue configuration file by using the request system configuration rescue save operational mode command. Each Junos OS device can have only one rescue configuration file."
Question #17
You have completed the initial configuration of your new Junos device. You want to be able to load this configuration at a later time.
Which action enables you to perform this task?
- A . Enter the load factory-default command.
- B . Enter the request system reboot command.
- C . Enter the request system zeroize command.
- D . Enter the request system configuration rescue save command.
Correct Answer: D
D
Explanation:
In Junos OS, the request system configuration rescue save command is used to save the current active configuration as a rescue configuration. This feature is particularly useful for preserving a known good configuration state that can be quickly reverted to in case of configuration errors or issues. By saving a rescue configuration, administrators can ensure that they have a reliable fallback option that can be loaded in the future to restore the device’s operation without having to reconfigure from scratch. This is an essential practice for maintaining network stability and quick recovery.
D
Explanation:
In Junos OS, the request system configuration rescue save command is used to save the current active configuration as a rescue configuration. This feature is particularly useful for preserving a known good configuration state that can be quickly reverted to in case of configuration errors or issues. By saving a rescue configuration, administrators can ensure that they have a reliable fallback option that can be loaded in the future to restore the device’s operation without having to reconfigure from scratch. This is an essential practice for maintaining network stability and quick recovery.
Question #18
Which protocol is responsible for learning an IPv4 neighbor’s MAC address?
- A . Address Resolution Protocol (ARP)
- B . Network Address Translation (NAT)
- C . Media Access Control Security (MACsec)
- D . Neighbor Discovery Protocol (NDP)
Correct Answer: A
A
Explanation:
The Address Resolution Protocol (ARP) is responsible for mapping an IPv4 address to a machine’s MAC address. ARP operates at Layer 2 of the OSI model and is used to find the MAC address of a host given its IPv4 address. When a device wants to communicate with another device on the same local network, it uses ARP to discover the recipient’s MAC address.
Reference: Juniper official documentation: ARP.
Networking standards: RFC 826.
A
Explanation:
The Address Resolution Protocol (ARP) is responsible for mapping an IPv4 address to a machine’s MAC address. ARP operates at Layer 2 of the OSI model and is used to find the MAC address of a host given its IPv4 address. When a device wants to communicate with another device on the same local network, it uses ARP to discover the recipient’s MAC address.
Reference: Juniper official documentation: ARP.
Networking standards: RFC 826.
Question #19
Which Junos OS component is responsible for maintaining the forwarding table?
- A . Routing Engine
- B . chassis control daemon
- C . Packet Forwarding Engine
- D . management daemon
Correct Answer: C
C
Explanation:
The Packet Forwarding Engine (PFE) in Junos OS is responsible for maintaining the forwarding table. The PFE processes incoming packets, performs route lookups in the forwarding table, and forwards packets based on this information, offloading these tasks from the Routing Engine to ensure efficient packet forwarding.
C
Explanation:
The Packet Forwarding Engine (PFE) in Junos OS is responsible for maintaining the forwarding table. The PFE processes incoming packets, performs route lookups in the forwarding table, and forwards packets based on this information, offloading these tasks from the Routing Engine to ensure efficient packet forwarding.
Question #20
Your network infrastructure transports data, voice, and video traffic. Users are complaining that voice and video calls are not performing to their expectations.
In this scenario, which technology would you implement to improve voice and video performance on your network?
- A . NAT
- B . CoS
- C . STP
- D . IPv6
Correct Answer: B
B
Explanation:
In a network that carries diverse types of traffic like data, voice, and video, ensuring the performance of latency-sensitive applications such as voice and video calls is crucial. Class of Service (CoS) is a technology designed to prioritize network traffic, ensuring that critical applications like voice and video receive the necessary bandwidth and minimal latency. CoS mechanisms can include traffic classification, traffic policing, queue management, and scheduling. By implementing CoS, network administrators can assign higher priority to voice and video traffic, thus improving their performance across the network and addressing the users’ complaints about call quality.
B
Explanation:
In a network that carries diverse types of traffic like data, voice, and video, ensuring the performance of latency-sensitive applications such as voice and video calls is crucial. Class of Service (CoS) is a technology designed to prioritize network traffic, ensuring that critical applications like voice and video receive the necessary bandwidth and minimal latency. CoS mechanisms can include traffic classification, traffic policing, queue management, and scheduling. By implementing CoS, network administrators can assign higher priority to voice and video traffic, thus improving their performance across the network and addressing the users’ complaints about call quality.