Free JN0-280 Exam Dumps

A switch receives a frame with a MAC address of FF-FF-FF-FF-FF-FF. Which action will the switch take on this frame?

Correct Answer:A
AMAC address of FF-FF-FF-FF-FF-FFis the Ethernetbroadcast address. When a switch receives a frame with this destination MAC address, it is required to forward the frame to all interfaces except the one it was received on.
Step-by-Step Breakdown:
Broadcast Frame Handling:When a frame with the broadcast MAC address is received, the switch will flood it out of all active ports that belong to the same VLAN as the incoming frame. The broadcast frame is not sent back out of the ingress interface (the interface where the frame was originally received).
Purpose of Flooding:Broadcasting is used to ensure that the frame reaches all devices within the broadcast domain (all devices within the same VLAN), which may not have a specific entry for the MAC address in their MAC address table.
Juniper Reference:
Layer 2 Frame Forwarding: Juniper switches flood broadcast frames to all ports in the same VLAN, except the port the frame was received on.

Exhibit:

Referring to the exhibit, what is the route preference of the 172.25.11.254 next hop?

Correct Answer:A
In the exhibit, we see two next-hop addresses for the default static route (0.0.0.0/0):
The first next hop is172.25.11.254, with no specified preference.
The second next hop is172.25.11.200, with a specified preference of140.
Step-by-Step Breakdown:
Default Static Route Preference:If no preference is explicitly set for a next hop in Junos, it defaults to5for static routes.
Determining Preference:In this case, the next hop172.25.11.254does not have an explicit preference defined, so it will use the default value of5. The second next hop has a preference of140, which is higher,meaning it will only be used if the primary next hop is unavailable.
Juniper Reference:
Static Route Preference: In Junos, the default preference for static routes is5, and this value is applied unless overridden by the preference parameter.

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

Correct Answer:ACE
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 aninstance-type forwardingrouting 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 afilterto 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

set firewall family inet filter FBF-filter term 1 then routing-instance FBF-instance
RIB Group:ARIB (Routing Information Base) groupis 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
Juniper Reference:
FBF Configuration: Filter-based forwarding requires these specific steps to redirect traffic to a custom routing table based on filter criteria.

Exhibit:

Referring to the exhibit, which two statements are correct about default BGP advertisements? (Choose two.)

Correct Answer:BD
The exhibit shows a BGP peering scenario between three routers:router1androuter2are part of the same AS (AS65000), while theSP routeris in a different AS (AS65101). This indicates anEBGP (External BGP)peering between the SP router and router1, andIBGPbetween router1 androuter2.
Step-by-Step Breakdown:
Next-Hop Behavior in BGP:
IBGP: In IBGP, thenext-hop addressis not modified when advertising routes within the same AS. Thus, when router1 advertises routes learned from router2 to the SP router, it will keep thenext-hop addressof router1, not router2.
EBGP: In EBGP, thenext-hop addressis modified. When router1 receives routes from the SP router, it will advertise them to router2 with thenext-hop addressof router1.
Route Propagation:
Routes received byrouter1fromrouter2will be advertised to the SP router with router1 as the next hop.
Similarly, routes advertised by theSP routerwill be passed on to router2, with router1 remaining as the next hop.
Juniper Reference:
BGP Next-Hop: Juniper's BGP implementations follow standard BGP next-hop behavior, where the next-hop is modified in EBGP but not in IBGP, ensuring proper route advertisement across autonomous systems.

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

Correct Answer:B
When creating aLAG (Link Aggregation Group)in Junos, theduplex settingsandlink speedmust 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
Juniper Reference:
LAG Configuration: Duplex and link speed must be consistent across member interfaces to ensure proper LAG operation in Juniper devices.