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Free JN0-280 Exam Braindumps (page: 4)

Page 3 of 18
PDF with 65 Questions

Which statement is correct about a three-stage IP fabric underlay?

  1. Every ingress interface into the fabric is only two hops away from the egress interface.
  2. Every spine device can communicate directly with other spine devices.
  3. Every leaf device can communicate directly with other leaf devices.
  4. Every server that connects to a three-stage IP fabric must be multihomed.

Answer(s): A

Explanation:

In a three-stage IP fabric (also known as a Clos fabric), traffic between any two points (ingress to egress) in the fabric is only two hops away.
Step-by-Step Breakdown:
Three-Stage IP Fabric:
Leaf Layer: Leaf switches connect directly to servers and edge devices. Spine Layer: Spine switches provide connectivity between leaf switches but do not connect to each other directly.
Two-Hop Communication:
In this architecture, every leaf switch is connected to every spine switch. Therefore, when a packet enters the fabric via an ingress leaf switch, it is forwarded to a spine switch, which then directs the packet to the correct egress leaf switch. This path always involves exactly two hops:
Ingress leaf Spine Egress leaf.
Benefits:
This consistent two-hop path ensures predictable latency and makes the network highly scalable while maintaining low complexity.


Reference:

IP Fabric Architecture: This two-hop property of Clos fabrics is a hallmark of spine-leaf designs, as supported by Juniper's QFX and EX switches in data centers.



A routing policy has been created to advertise OSPF routes in BGP.
Which statement is correct in this scenario?

  1. Apply the policy as an export policy within BGP.
  2. Apply the policy as an export policy within OSPF.
  3. Apply the policy as an import policy within BGP.
  4. Apply the policy as an import policy within OSPF.

Answer(s): A

Explanation:

When advertising OSPF routes into BGP, the appropriate routing policy should be applied as an export policy in BGP.
Step-by-Step Breakdown:
OSPF to BGP Route Advertisement:
Routes learned via OSPF (a dynamic IGP) need to be exported into BGP to be advertised to external BGP peers. In Junos OS, this is done using export policies.
Export Policies in BGP:
An export policy controls which routes are advertised out of a BGP session. In this scenario, the routing policy must be applied to BGP as an export policy to export the OSPF-learned routes to external BGP peers.
Policy Configuration:

Example configuration:

set policy-options policy-statement EXPORT_OSPF term 1 from protocol ospf set policy-options policy-statement EXPORT_OSPF term 1 then accept set protocols bgp group <group-name> export EXPORT_OSPF This policy ensures that only OSPF routes are exported into BGP.


Reference:

Routing Policy: Export policies are used in BGP to control route advertisements to peers, including those learned via OSPF.



Which statement is correct about member interfaces when creating a LAG?

  1. The interface's MTU settings must match on all member interfaces.
  2. The interface's duplex settings and link speed must be the same on all member interfaces.
  3. Member interfaces must all be allocated on the same chassis when using a Virtual Chassis.
  4. Member interfaces must all be allocated on the same PFE.

Answer(s): B

Explanation:

When creating a LAG (Link Aggregation Group) in Junos, the duplex settings and link speed must be the same across all member interfaces.
Step-by-Step Breakdown:
LAG Overview:
A LAG combines multiple physical interfaces into a single logical interface to increase bandwidth and provide redundancy. All member links must act as a single cohesive unit.
Interface Requirements:
Duplex: All member interfaces must operate in the same duplex mode (either full-duplex or half- duplex). Mismatched duplex settings can cause performance issues, packet drops, or interface errors. Link Speed: All interfaces in the LAG must have the same link speed (e.g., all interfaces must be 1 Gbps or 10 Gbps). Mismatched speeds would prevent the interfaces from functioning correctly within the LAG.
Configuration and Validation: Ensure that all member interfaces have identical settings before adding them to the LAG. These settings can be checked using the show interfaces command, and the LAG

can be configured using:

set interfaces ae0 aggregated-ether-options link-speed 10g set interfaces ge-0/0/1 ether-options 802.3ad ae0


Reference:

LAG Configuration: Duplex and link speed must be consistent across member interfaces to ensure proper LAG operation in Juniper devices.



Which three actions are required to implement filter-based forwarding? (Choose three.)

  1. You must create an instance-type forwarding routing instance.
  2. You must create an instance-type vrf routing instance.
  3. You must create a match filter.
  4. You must create a security policy.
  5. You must create a RIB group.

Answer(s): A,C,E

Explanation:

Filter-Based Forwarding (FBF) in Junos OS allows traffic to be routed based on specific criteria such as source address, rather than just the destination address. This is useful in scenarios like policy routing or providing multiple paths for different types of traffic.
Step-by-Step Breakdown:
Instance-Type Forwarding:
You must create an instance-type forwarding routing instance. This routing instance allows for different routing tables based on the incoming packet filter.
Command:

set routing-instances FBF-instance instance-type forwarding Match Filter:
You need to create a filter to match the traffic that will be forwarded according to your custom routing policy. This filter is applied to an interface to determine which traffic will use the custom forwarding instance.
Command Example:

set firewall family inet filter FBF-filter term 1 from source-address <address> set firewall family inet filter FBF-filter term 1 then routing-instance FBF-instance RIB Group:
A RIB (Routing Information Base) group is necessary to share routes between the primary routing table and the custom routing instance. This allows FBF traffic to use the routing information from other routing tables.
Command Example:

set routing-options rib-groups FBF-group import-rib inet.0 set routing-instances FBF-instance routing-options rib-group FBF-group


Reference:

FBF Configuration: Filter-based forwarding requires these specific steps to redirect traffic to a custom routing table based on filter criteria.






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