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Free JN0-280 Exam Braindumps (page: 6)

Page 5 of 18
PDF with 65 Questions

What information in the Ethernet header is used to populate the bridging table?

  1. destination address
  2. source address
  3. type
  4. protocol

Answer(s): B

Explanation:

The source MAC address in the Ethernet header is used to populate the bridging table (also called the MAC address table) on a switch.
When a frame arrives at a switch, the switch examines the source MAC address and records it along with the ingress port in its MAC address table.
Step-by-Step Breakdown:
Learning Process:
When an Ethernet frame arrives on a switch port, the switch looks at the source MAC address and adds this MAC address to the MAC table along with the port it was received on. This process is called MAC learning.
Purpose:
The switch uses this information to determine the correct port to send frames destined for that MAC address in future transmissions, thus ensuring efficient Layer 2 forwarding.


Reference:

Ethernet Switching: Juniper switches use source MAC addresses to build and maintain the MAC address table, which is essential for Layer 2 switching.



You are configuring an aggregate route. In this scenario, which two statements are correct? (Choose two.)

  1. Reject will silently drop the traffic.
  2. Discard will silently drop the traffic.
  3. Reject will send an ICMP Destination Unreachable message back to the sender.
  4. Discard will send an ICMP Destination Unreachable message back to the sender.

Answer(s): B,C

Explanation:

When configuring an aggregate route, you have options for how to handle traffic that matches the route but does not match any more specific route in the routing table. Two actions can be taken:
discard and reject.
Step-by-Step Breakdown:
Discard:
The discard option will silently drop packets that match the aggregate route. No notification is sent to the sender, and the packet is simply dropped.
Reject:
The reject option will drop the packet and also send an ICMP Destination Unreachable message back to the sender. This informs the sender that the packet could not be delivered because there is no specific route available.


Reference:

Aggregate Routes: The reject and discard next-hop options provide different levels of feedback when packets cannot be routed, and they can be used to control how unreachable destinations are handled.



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

  1. a Layer 3 routing protocol
  2. a single connection between each spine and leaf
  3. a single connection between each leaf
  4. a Layer 2 switching protocol

Answer(s): A,B

Explanation:

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 to every 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.


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.



What is the main purpose of Bidirectional Forwarding Detection (BFD)?

  1. to detect network path failures
  2. to determine if the forwarding routes are correct
  3. to detect the forwarding protocol
  4. to determine packet round-trip latency

Answer(s): A

Explanation:

Bidirectional Forwarding Detection (BFD) is a network protocol used to detect failures in the network path between two devices quickly.
Step-by-Step Breakdown:
Path Failure Detection:
BFD provides a low-overhead mechanism for detecting failures in forwarding paths across Layer 3 networks. It is much faster than traditional routing protocol timers and can detect failures within milliseconds.
BFD in Routing:
BFD can be integrated with routing protocols like OSPF, BGP, or IS-IS to trigger a faster convergence when a network path goes down.


Reference:

BFD Configuration: Juniper devices use BFD to monitor network paths and ensure fast failure detection, enhancing network resilience.






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