Juniper JN0-280 Online Practice Questions and Exam Preparation

Juniper JN0-280 Online Questions & Answers

• Question 101:

  In the context of Link Aggregation Groups (LAG), what is the primary purpose of LACP?

  A. To provide a method for encrypting data packets
  B. To dynamically manage the bundling of several physical ports
  C. To reduce the speed of data transfer
  D. To increase the error rate in data transmission
  B. To dynamically manage the bundling of several physical ports

• Question 102:

  You want to minimize topology disruptions in your network when the rpd process restarts on a device. Which service would accomplish this task?

  A. Bidirectional Forwarding Detection (BFD)
  B. link aggregation groups
  C. graceful restart (GR)
  D. Virtual Chassis
  C. graceful restart (GR)

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  Explanation/Reference:

  Graceful Restart (GR)is a feature that allows a router to maintain forwarding even when the routing process (e.g., the rpd process in Junos) is restarting, minimizing disruption to the network.

  Step-by-Step Breakdown:

  Graceful Restart Function:During a GR event , the forwarding plane continues to forward packets based on existing routes, while the control plane (rpd process) is restarting. This prevents traffic loss and maintains routing stability. Minimizing

  Disruptions:GR is particularly useful in ensuring continuous packet forwarding during software upgrades or routing protocol process restarts.

  Juniper Reference:

  Graceful Restart in Junos: GR ensures high availability by maintaining forwarding continuity during control plane restarts, enhancing network reliability.

• Question 103:

  What protocol and port does BGP use for control plane communication?

  A. protocol TCP, port 179
  B. protocol UDP, port 179
  C. protocol TCP, port 159
  D. protocol UDP, port 159
  A. protocol TCP, port 179

• Question 104:

  Which operation mode command will display the mapping between the VLAN ID and ports on a switch?

  A. show route
  B. show ethernet-switching table
  C. show interfaces terse
  D. show vlans
  D. show vlans

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  Explanation/Reference:

  To display the mapping between VLAN IDs and ports on a Juniper switch, the show vlans command is used.

  Step-by-Step Breakdown:

  VLAN Information:The show vlans command displays detailed information about VLAN configurations, including the VLAN ID, associated interfaces (ports), and VLAN membership.

  Command Example:

  show vlans

  This command will provide an output listing each VLAN, its ID, and the interfacesassociated with the VLAN, enabling network engineers to quickly verify VLAN to port mappings.

  Juniper Reference:

  VLAN Verification: Use the show vlans command to verify which VLANs are configured on the switch and the ports that are members of those VLANs.

• Question 105:

  Which route is preferred by the Junos OS software routing tables?

  A. Static
  B. Aggregate
  C. Direct
  D. BGP
  C. Direct

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  Explanation/Reference:

  In Junos OS, direct routes are the most preferred routes in the routing table, having the highest priority.

  Step-by-Step Breakdown:

  Direct Routes:

  Direct routes represent networks that are directly connected to the router's interfaces. Since these routes are directly accessible, they are assigned the highest priority and always take precedence over other types of routes.

  Preference Values:

  Direct routes have a preference of 0 , which is the most preferred in Junos. Static routes, OSPF routes, and BGP routes have higher preference values and will only be used if there are no direct routes to the destination.

  Juniper Reference:

  Direct Route Preference: In Junos, direct routes are always preferred over other routes, ensuring that the router forwards traffic through locally connected networks.

• Question 106:

  What does the "qualified-next-hop" feature do when configuring a static route?

  A. It allows you to specify an independent route preference value for an additional next hop.
  B. It specifies the IP address of the directly connected device.
  C. It instructs the device to verify the next-hop is reachable before activating the route.
  D. It instructs the device to looks up a static route's next-hop that is not directly connected.
  A. It allows you to specify an independent route preference value for an additional next hop.

• Question 107:

  What is the primary difference between IBGP and EBGP?

  A. The way they advertise routes
  B. The administrative distance
  C. The use of AS_PATH attribute
  D. The requirement for a full mesh topology
  B. The administrative distance

• Question 108:

  In OSPF, which command is commonly used to monitor neighbor relationships?

  A. show ip ospf neighbors
  B. show ospf database
  C. show ip route ospf
  D. show ospf interfaces
  A. show ip ospf neighbors

• Question 109:

  Which three technologies improve high availability and convergence in a data center network? (Choose three.)

  A. graceful restart (GR)
  B. Bidirectional Forwarding Detection (BFD)
  C. link loss adjacency
  D. Failover Group (FG)
  E. link aggregation group (LAG)
  A. graceful restart (GR)
  B. Bidirectional Forwarding Detection (BFD)
  E. link aggregation group (LAG)

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  Explanation/Reference:

  High availability and fast convergence are critical in data center networks to minimize downtime and maintain optimal performance. The following technologies contribute to achieving these goals:

  Graceful Restart (GR):

  GR allows routers to maintain forwarding state during control plane restarts, ensuring continuous packet forwarding while minimizing network disruptions.

  Bidirectional Forwarding Detection (BFD):

  BFD provides fast detection of path failures, allowing routing protocols to converge quickly by detecting link failures much faster than traditional timers.

  Link Aggregation Group (LAG):

  LAG increases both redundancy and bandwidth by combining multiple physical links into one logical link, providing load balancing and fault tolerance.

  Juniper Reference:

  High Availability Techniques: These technologies are fundamental in ensuring rapid recovery and failover within Juniper-based data center environments.

• Question 110:

  Which two statements are correct about VLAN tags? (Choose two.)

  A. VLAN tags carry a VLAN ID and priority.
  B. VLAN tags are required on access ports.
  C. VLAN tags require multiple forwarding tables.
  D. VLAN tags can be inserted or removed by trunk interfaces.
  A. VLAN tags carry a VLAN ID and priority.
  D. VLAN tags can be inserted or removed by trunk interfaces.

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  Explanation/Reference:

  VLAN tagsare used in Ethernet frames to identify and differentiate traffic between multiple VLANs. They are especially important for devices like switches that handle multiple VLANs on the same physical link.

  Step-by-Step Breakdown:

  VLAN Tag Contents:

  VLAN ID: The tag contains a 12-bit VLAN ID field that identifies the VLAN to which the frame belongs.

  Priority: The tag also includes a 3-bit priority field (also known as 802.1p priority) used for QoS (Quality of Service) to prioritize traffic.

  Trunk Ports and VLAN Tagging:

  Trunk Portsare used to carry traffic for multiple VLANs across a single link. These interfaces insert (tag) VLAN identifiers into frames when they leave the switch and remove (untag) them when frames enter the switch. Access Ports:VLAN

  tags are typically not used on access ports (ports that connect to end devices) since those ports are configured to be part of a single VLAN, and the traffic doesn't need VLAN tags.

  Juniper Reference:

  VLAN Tagging: Juniper switches support VLAN tagging and ensure that frames are tagged or untagged as they traverse trunk or access ports, respectively.