Juniper JN0-105 Online Practice Questions and Exam Preparation

Juniper JN0-105 Online Questions & Answers

• Question 81:

  A network administrator is attempting to route traffic on a Juniper switch to one of three different VLANs: Prod, Test, and Dev. Each VLAN has been assigned a numerical value. In this scenario, what are these numerical values called?

  A. defaults
  B. interfaces
  C. names
  D. tags
  D. tags

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  Explanation

  In the context of VLANs (Virtual Local Area Networks) on a Juniper switch, the numerical values assigned to each VLAN, such as those for Prod, Test, and Dev, are known as VLAN tags. These tags are part of the 802.1Q VLAN standard, which allows multiple VLANs to coexist on a single physical network. Each tag uniquely identifies the VLAN to which a frame belongs, enabling the switch to segregate and manage traffic based on VLAN membership. This tagging mechanism allows for efficient traffic separation and management, ensuring that devices within one VLAN do not receive traffic intended for another, thus maintaining network security and efficiency.

• Question 82:

  Click the Exhibit button.

  

  How is traffic, sourced from 10.0.0.0/8, treated by the firewall filter shown in the exhibit?

  A. logged with no further action
  B. logged and accepted
  C. logged and rejected
  D. logged and discarded
  B. logged and accepted

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  Explanation

  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.

• Question 83:

  Which two fields are you required to enter when you create a new user account? (Choose two.)

  A. login class
  B. username
  C. user ID
  D. full name
  A. login class
  B. username

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  Explanation

  In Junos OS, when creating a new user account, the minimum required fields are the username and the login class. The username is the identifier for the account, while the login class specifies the level of access or permissions the user has on the device. Login classes allow for the differentiation between various roles, such as read-only access or full administrative rights. Other information, such as full name or user ID, is optional and not strictly necessary for the creation of a functional user account.

• Question 84:

  Which three statements are true about IPv6 linl local addresses? (Choose three.)

  A. They begin with the prefix fe80::/64.
  B. They can be assigned manually or dynamically.
  C. They are not guaranteed to be unique outside of the network segment.
  D. They are optional adddresses.
  E. They provide reachability to the internet.
  A. They begin with the prefix fe80::/64.
  B. They can be assigned manually or dynamically.
  C. They are not guaranteed to be unique outside of the network segment.

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  Explanation

• Question 85:

  Which two statements are true about the Junos OS? (Choose two.)

  A. Routing tables are stored in the control plane.
  B. Routing tables are stored in the forwarding plane.
  C. Exception traffic is never sent to the control plane.
  D. Exception traffic is sent to the control plane.
  A. Routing tables are stored in the control plane.
  D. Exception traffic is sent to the control plane.

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  Explanation

  In Junos OS, as with many network operating systems, the control plane is responsible for processes that determine how to route traffic. This includes maintaining routing tables, which store information about network paths and protocols.

  Therefore, routing tables are indeed stored in the control plane. Exception traffic refers to packets that cannot be processed by the normal fast-path processing of the Packet Forwarding Engine (PFE) in the forwarding plane, and thus are sent

  to the control plane for further processing. This might include packets destined for the router itself, packets that need to be fragmented, or packets that match certain firewall filter criteria, among other reasons.

  Routing tables are not stored in the forwarding plane. However, the forwarding plane contains the forwarding table (sometimes referred to as the forwarding information base or FIB), which is a distilled version of the routing table optimized for

  fast packet forwarding. The forwarding plane uses this information to perform the actual transfer of packets across the network device interfaces.

• Question 86:

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

  A. 3
  B. 1
  C. 50
  D. 49
  B. 1

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  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.

  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 87:

  You have configured some interfaces on a Junos device; however, you have not yet committed the configuration.

  What happens if you issue the rollback 0 command in this scenario?

  A. The messages.log file is deleted.
  B. The interface changes you made are discarded.
  C. The factory default configuration is loaded.
  D. The Junos device is rebooted.
  B. The interface changes you made are discarded.

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  Explanation

  Issuing the rollback 0 command in Junos OS will discard any uncommitted changes and revert to the last committed configuration. This command effectively cancels any configuration changes that have been made but not yet committed,

  ensuring that the device returns to its previous stable state.

  References:

  "rollback 0 ...................................(rolls back the changes just made )" from Useful Juniper Commands.txt.

  Juniper official documentation: Rolling Back a Configuration.

• Question 88:

  How many login classes are assignable to a user account?

  B. 1

  C. 4

  D. 3

  Correct Answer. B
  B

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  Explanation

  In Junos OS, each user account can be assigned only one login class. Login classes in Junos OS define the permissions for users, controlling what they can access and modify within the system. This setup helps in maintaining a clear and

  secure access control mechanism.

  Junos OS Documentation on User Accounts and Login Classes.

• Question 89:

  Which component is considered part of the data plane?

  A. the Packet Forwarding Engine
  B. the fan tray
  C. the power supply
  D. the Routing Engine
  A. the Packet Forwarding Engine

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  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 90:

  Which command causes the Junos OS to temporarily activate a configuration?

  A. commit and-quite
  B. commit synchronize
  C. commit check
  D. commit confirmed
  D. commit confirmed

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  Explanation