Juniper JN0-280 Online Practice Questions and Exam Preparation

Juniper JN0-280 Online Questions & Answers

• Question 81:

  When evaluating BGP routes, what will be evaluated first?

  A. The local preference value
  B. The AS path
  C. The MED value
  D. The origin value
  A. The local preference value

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  Explanation/Reference:

  In BGP (Border Gateway Protocol) , when evaluating multiple routes to the same destination, the first attribute that is considered is the local preference value. The local preference is a BGP attribute used to influence outbound routing

  decisions within an Autonomous System (AS).

  Step-by-Step Breakdown:

  Local Preference:The local preference attribute is used to determine which path is preferred for traffic leaving the AS. The higher the local preference value, the more preferred the route.

  BGP Path Selection:The BGP path selection process evaluates the following attributes in this order:

  Local Preference(higher is preferred)

  AS Path(shorter is preferred)

  Origin(IGP > EGP > incomplete)

  MED (Multi-Exit Discriminator)(lower is preferred)

  Juniper Reference:

  BGP Path Selection: In Junos, the local preference attribute is the first to be evaluated when determining the best path for outbound traffic.

• Question 82:

  What are three correct layer names used in legacy hierarchical network design? (Choose three.)

  A. Access layer
  B. Modular layer
  C. Aggregation layer
  D. Core layer
  E. Function layer
  A. Access layer
  C. Aggregation layer
  D. Core layer

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  Explanation/Reference:

  In legacy hierarchical network design , three key layers are used to create a scalable and structured network:

  Step-by-Step Breakdown:

  Access Layer:

  The access layer is where end devices, such as computers and IP phones, connect to the network. It typically involves switches that provide connectivity for devices at the edge of the network.

  Aggregation Layer (Distribution Layer):

  The aggregation layer (also called the distribution layer) aggregates traffic from multiple access layer devices and applies policies such as filtering and QoS. It also provides redundancy and load balancing.

  Core Layer:

  The core layer provides high-speed connectivity between aggregation layer devices and facilitates traffic within the data center or between different network segments.

  Juniper Reference:

  Legacy Hierarchical Design: Juniper networks often follow the traditional three-layer design (Access, Aggregation, and Core) to ensure scalability and high performance.

• Question 83:

  What does filter-based forwarding in networking typically allow?

  A. Forwarding decisions based on MAC addresses
  B. Load balancing across multiple CPUs
  C. Routing decisions based on extended criteria like packet headers
  D. Aggregation of multiple routes into a single entry
  C. Routing decisions based on extended criteria like packet headers

• Question 84:

  Within your router, you want to verify that you are learning routes from a remote BGP peer at IP address 10.10.100.1. Which command would satisfy the requirement?

  A. show route receive-protocol bgp 10.10.100.1
  B. show route protocol bgp table inet.0 10.10.100.1
  C. show route advertise-protocol bgp 10.10.100.1
  D. show route protocol bgp source-gateway 10.10.100.1
  A. show route receive-protocol bgp 10.10.100.1

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  Explanation/Reference:

  To verify that your router is learning routes from a remote BGP peer at a specific IP address (e.g., 10.10.100.1), the correct command to use is show route receive-protocol bgp.

  Step-by-Step Breakdown:

  BGP Route Learning:The show route receive-protocol bgp command displays the routes that have been received from a specified BGP peer. This helps in confirming that the remote peer is sending routes correctly and that your router is

  receiving them.

  Command Example:

  show route receive-protocol bgp 10.10.100.1

  This will show all routes that have been received from the BGP peer with IP address 10.10.100.1.

  Juniper Reference:

  BGP Route Verification: Use this command to troubleshoot and verify that routes from a specific BGP peer are being received.

• Question 85:

  With regards to graceful restart, which two statements are true? (Choose two.)

  A. A supported routing protocol, such as BGP, must be operational for graceful restart to work.
  B. NSR must be enabled for graceful restart to work.
  C. Dual routing engines are required for graceful restart to work.
  D. The network topology must be stable for graceful restart to work.
  A. A supported routing protocol, such as BGP, must be operational for graceful restart to work.
  D. The network topology must be stable for graceful restart to work.

• Question 86:

  Which LSA types are associated with OSPF? (Choose three)

  A. Router LSA (Type 1)
  B. Network LSA (Type 2)
  C. Summary LSA (Type 3)
  D. External LSA (Type 5)
  A. Router LSA (Type 1)
  B. Network LSA (Type 2)
  C. Summary LSA (Type 3)

• Question 87:

  What is the primary purpose of an IRB Layer 3 interface?

  A. to provide load balancing
  B. to provide a default VLAN ID
  C. to provide inter-VLAN routing
  D. to provide port security
  C. to provide inter-VLAN routing

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  Explanation/Reference:

  The primary purpose of an IRB (Integrated Routing and Bridging) interface is to enable inter-VLAN routing in a Layer 3 environment. An IRB interface in Junos combines the functionality of both Layer 2 bridging (switching) and Layer 3 routing,

  allowing devices in different VLANs to communicate with each other.

  Step-by-Step Breakdown:

  VLANs and Layer 2 Switching:Devices within the same VLAN can communicate directly through Layer 2 switching. However, communication between devices in different VLANs requires Layer 3 routing. IRB Interface for Inter-VLAN

  Routing:The IRB interface provides a Layer 3 gateway for each VLAN, enabling routing between VLANs. Without an IRB interface, devices in different VLANs would not be able to communicate. Configuration:In Juniper devices, the IRB

  interface is configured by assigning Layer 3 IP addresses to it. These IP addresses serve as the default gateway for devices in different VLANs.

  Example configuration:

  set interfaces irb unit 0 family inet address 192.168.1.1/24

  set vlans vlan-10 l3-interface irb.0

  This allows VLAN 10 to use the IRB interface for routing.

  Juniper Reference:

  IRB Use Case: Inter-VLAN routing is essential in data centers where multiple VLANs are deployed, and Juniper's EX and QFX series switches support IRB configurations for this purpose.

• Question 88:

  What is an advantage of using BFD?

  A. BFD is so lightweight that each protocol will generate its own unique BFD session by default, to replace its own hello messages.
  B. BFD built to handle the routing table of the entire Internet, and can safely redistribute it into OSP
  C. One BFD monitoring session can be used by multiple protocols.
  D. BFD is built to handle the routing table of the entire Internet, unlike IGP
  C. One BFD monitoring session can be used by multiple protocols.

• Question 89:

  Referring to the exhibit, which two statements are true? (Choose two.)

  

  A. The configuration will not pass the commit check.
  B. The BGP group is configured to attempt an EBGP peering session with 192.168.100.2.
  C. The configuration will pass the commit check.
  D. The BGP group is configured to attempt an EBGP peering session with 192.168.100.1.
  A. The configuration will not pass the commit check.
  B. The BGP group is configured to attempt an EBGP peering session with 192.168.100.2.

• Question 90:

  Which statement is correct about per-flow load balancing?

  A. Packets associated with the same flow are sent through different egress ports.
  B. The packets are guaranteed to arrive at their destination in a different order in which they were sent.
  C. Packets associated with the same flow are sent through the same egress port.
  D. The packets are guaranteed to arrive at their destination in the same order in which they were sent.
  C. Packets associated with the same flow are sent through the same egress port.

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  Explanation/Reference:

  Per-flow load balancingensures that packets within the same flow are always forwarded over the same path, ensuring that packet order is preserved.

  Step-by-Step Breakdown:

  Flow Definition:A flow is typically defined by a combination of packet attributes like source /destination IP, source/destination port, and protocol type. Packets that belong to the same flow are routed over the same path to avoid reordering. Per-

  Flow Behavior:In per-flow load balancing , the hashing algorithm ensures that all packets in a particular flow use the same egress port , maintaining order across the network.

  Juniper Reference:

  Load Balancing in Juniper: This method ensures that flows are balanced across multiple paths while preventing packet reordering within a single flow.