Juniper JN0-280 Online Practice Questions and Exam Preparation

Juniper JN0-280 Online Questions & Answers

• Question 51:

  What is the primary role of an IRB interface in a VLAN configuration?

  A. To provide a gateway for VLAN traffic.
  B. To encrypt VLAN traffic.
  C. To prioritize VLAN traffic.
  D. To filter VLAN traffic based on MAC addresses.
  A. To provide a gateway for VLAN traffic.

• Question 52:

  In networking, what is a RIB group primarily used for?

  A. To balance the load across multiple links
  B. To filter routes based on specific criteria
  C. To group multiple Routing Information Bases together for a common purpose
  D. To dynamically generate routing entries
  C. To group multiple Routing Information Bases together for a common purpose

• Question 53:

  What are two characteristics of a typical EBGP underlay fabric? (Choose two.)

  A. Each device in an EBGP fabric will be configured in its own unique private A
  B. Each device in an EBGP fabric will be configured to be part of the same private A
  C. An EBGP fabric relies on an IGP to advertise loopback IPs.
  D. An EBGP fabric does not require an IGP to advertise loopback IPs.
  A. Each device in an EBGP fabric will be configured in its own unique private A
  D. An EBGP fabric does not require an IGP to advertise loopback IPs.

• Question 54:

  What are two requirements for an IP fabric? (Choose two.)

  A. a Layer 3 routing protocol
  B. a single connection between each spine and leaf
  C. a single connection between each leaf
  D. a Layer 2 switching protocol
  A. a Layer 3 routing protocol
  B. a single connection between each spine and leaf

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  Explanation/Reference:

  An IP fabric is a network architecture commonly used in data centers to provide scalable, high-throughput connectivity using a spine-leaf topology .

  Step-by-Step Breakdown:

  Layer 3 Routing Protocol:An IP fabric relies on a Layer 3 routing protocol , typically BGP or OSPF, to provide routing between the leaf and spine switches. This ensures efficient traffic forwarding across the network. Single Connection

  Between Spine and Leaf:In an IP fabric, each leaf switch connects toevery spine switch with a single connection. This ensures that traffic between any two leaf switches can travel through the spine layer in just two hops.

  Juniper Reference:

  Spine-Leaf Design: Juniper's IP fabric implementations are designed for scalability and low-latency routing, often using protocols like BGP for Layer 3 control.

• Question 55:

  Which static routing parameter will silently drop the packet if it is set as the next hop?

  A. Reject
  B. Resolve
  C. Readvertise
  D. Discard
  D. Discard

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  Explanation/Reference:

  When the discard option is configured as the next hop for a static route, it silently drops any packets that match the route without sending any notification to the sender.

  Step-by-Step Breakdown:

  Discard Behavior:

  If a route uses the discard next hop, the router drops the packet without generating any ICMP message or error back to the sender. This is useful for creating null routes to prevent routing loops or blackhole traffic intentionally.

  Reject vs. Discard:

  The reject next hop, in contrast, drops the packet but sends an ICMP Destination Unreachable message back to the source.

  Juniper Reference:

  Static Route Behavior: In Junos, the discard option ensures packets matching a static route are dropped silently, providing a way to discard traffic without alerting the source.

• Question 56:

  When a MAC limiting violation occurs, the switch performs which two actions by default? (Choose two.)

  A. No logging takes place.
  B. It causes Layer 2 loops.
  C. The port is disabled.
  D. It drops the packet.
  C. The port is disabled.
  D. It drops the packet.

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  Explanation/Reference:

  When a MAC limiting violation occurs on a Juniper switch, the switch will perform the following actions by default:

  Step-by-Step Breakdown:

  Port Disabled:When the number of MAC addresses on an interface exceeds the configured limit, the port is automatically disabled to prevent further violations. This is a protective mechanism to prevent MAC address flooding. Packet

  Dropped:Additionally, packets from the violating MAC address are dropped to prevent any further communication from that address. This ensures that only valid MAC addresses are allowed to communicate through the interface.

  Example Configuration:

  set ethernet-switching-options secure-access-port interface mac-limit 5

  If more than five MAC addresses are learned, the port is disabled, and excess packets are dropped.

  Juniper Reference:

  MAC Limiting: When the switch detects a MAC limiting violation, it disables the port and drops further packets from the violating MAC addresses to maintain network security.

• Question 57:

  What is the definition of a trunk interface on a switch?

  A. An interface that carries multiple VLANs.
  B. An interface that carries high bandwidth.
  C. An interface that connects directly to powerful servers.
  D. An interface that carries excess traffic.
  A. An interface that carries multiple VLANs.

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  Explanation/Reference:

  A trunk interface on a switch is used to carry traffic for multiple VLANs between switches or between a switch and another network device, like a router. Trunk interfaces use 802.1Q tagging to identify which VLAN the traffic belongs to.

  Step-by-Step Breakdown:

  Trunk Ports:

  Trunk ports are typically used for inter-switch links or switch-to-router links where multiple VLANs need to be carried over the same physical connection.

  VLAN traffic is tagged with a VLAN ID to ensure that it is properly identified as it crosses the trunk link.

  802.1Q VLAN Tagging:

  Trunk ports use 802.1Q to tag Ethernet frames with the VLAN ID. This ensures that frames are correctly forwarded to the appropriate VLANs on the other side of the trunk.

  Juniper Reference:

  Trunk Interface Configuration: In Juniper switches, trunk ports are configured to carry tagged traffic for multiple VLANs, which is essential for interconnecting multiple network segments.

• Question 58:

  EVPN/VXLAN is primarily used in modern data centers to:

  A. Increase the physical distance between data centers.
  B. Provide Layer 2 connectivity over a Layer 3 network.
  C. Replace traditional routing protocols.
  D. Enhance the physical security of the data center.
  B. Provide Layer 2 connectivity over a Layer 3 network.

• Question 59:

  What is the primary purpose of using static routes in a network?

  A. To automatically adjust routes based on network traffic
  B. To provide a manually configured routing entry
  C. To aggregate multiple routes into one
  D. To generate routing entries dynamically
  B. To provide a manually configured routing entry

• Question 60:

  Which two statements are true about how switches handle Layer 2 traffic? (Choose two.)

  A. The MAC address is learned based on the destination MAC address.
  B. The MAC address is learned based on the source MAC address.
  C. Traffic is forwarded based on the source MAC address.
  D. Traffic is forwarded based on the destination MAC address.
  B. The MAC address is learned based on the source MAC address.
  D. Traffic is forwarded based on the destination MAC address.

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  Explanation/Reference:

  In Layer 2 switching, switches learn MAC addresses based on the source MAC address of incoming frames and forward frames based on the destination MAC address .

  Step-by-Step Breakdown:

  MAC Learning:When a switch receives a frame, it records the source MAC address and the port on which it arrived. This allows the switch to know where to send traffic destined for that MAC address. Forwarding Based on Destination:The

  switch then looks at the destination MAC address and forwards the frame out of the port associated with that MAC address. If the MAC is unknown, the switch floods the frame to all ports.

  Juniper Reference:

  Layer 2 Switching: Juniper switches use source MAC addresses to build MAC tables and forward traffic based on the destination MAC address.