Free Practice Questions for Nokia 4A0-D03 Exam

Comprehensive and Detailed 150 to 250 words of Explanation From [SR Linux EVPN and Data Center Interconnect/Course Guide/topics]:

In an SR Linux Layer 2 EVPN MAC-VRF, locally attached MAC addresses are learned through the data plane on local access interfaces, while remote MAC addresses are learned from MP-BGP EVPN control-plane advertisements and installed with a VXLAN next-hop. The exhibit shows one local learned MAC on an Ethernet subinterface and another MAC learned through EVPN with a VXLAN interface and VNI 100. The remote VTEP or next-hop information identifies the remote endpoint, and the VNI maps the received VXLAN traffic to the correct MAC-VRF service. The false statement is C because saying that the MAC address associated with the vxlan-interface “will not age out” is too absolute. A remote EVPN MAC is not aged in the same way as a local data-plane-learned MAC, but it can still be removed when the corresponding EVPN route is withdrawn, invalidated, or no longer present in the control plane. The “N/A” style aging behavior does not mean permanent retention. Reference: SR Linux MAC-VRF verification, local MAC learning, EVPN-learned remote MACs, VXLAN VNI mapping.

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Comprehensive and Detailed 150 to 250 words of Explanation From [SR Linux EVPN and Data Center Interconnect/Course Guide/topics]:

Ethernet Auto-Discovery per EVI information is used in EVPN multi-homing to advertise that a PE has reachability to a particular Ethernet Segment for a specific EVPN instance. Remote PEs use this information for aliasing, allowing them to forward known unicast traffic toward a multi-homed Ethernet Segment through eligible PEs rather than relying only on the PE that advertised a specific MAC route. In VXLAN-based EVPN, the update also carries information needed by remote peers to select the proper data-plane encapsulation and VNI for the service. The multi-homing behavior advertised with the Ethernet Segment enables remote peers to understand whether the attachment is operating in all-active or single-active mode. Option D is the false statement in this context because route-target handling is a general BGP EVPN import/export mechanism associated with VPN route policy and extended communities; it is not the specific operational function that defines AD per EVI behavior. The AD per EVI route's purpose is Ethernet Segment reachability for an EVI, not route-target-based service identification by itself. Reference: EVPN route type 1, AD per EVI, aliasing and multi-homing signaling.

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Comprehensive and Detailed 150 to 250 words of Explanation From [SR Linux EVPN and Data Center Interconnect/Course Guide/topics]:

PE-CE routing is the mechanism used to exchange customer prefix reachability between a provider edge or data center leaf and the attached customer edge router. It can be implemented statically or dynamically. Static routing is operationally simple but does not scale well when many prefixes or frequent changes are involved. BGP is preferred for larger deployments because it supports policy, route filtering, attributes, and automated advertisement of changing reachability. In most EVPN PE-CE designs, eBGP is preferred because it creates a clean routing boundary between the PE and CE, with each device operating in a different autonomous system. Option D is false because the CE does not advertise BGP EVPN route type 5 updates to the PE. The CE advertises ordinary IPv4 or IPv6 unicast prefixes over the PE-CE routing session. The PE then imports those customer prefixes into the IP-VRF and advertises them into the EVPN overlay as route type 5 IP Prefix routes toward other PEs. This distinction matters: EVPN signaling is a PE-to-PE overlay function, not a CE-originated EVPN control-plane role. Reference: PE-CE routing, eBGP, EVPN RT-5 prefix advertisement.

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Comprehensive and Detailed 150 to 250 words of Explanation From [SR Linux EVPN and Data Center Interconnect/Course Guide/topics]:

The exhibit describes an EVPN IRB environment where MAC-VRF100 and IP-VRF-100 exchange host reachability through local learning and EVPN advertisements. Leaf-1 can advertise EVPN route type 2 updates containing host MAC/IP information for MAC-VRF100. This is the normal mechanism used to distribute endpoint bindings learned from local hosts. If IP-VRF-100 is not configured for prefix advertisement, Leaf-1 will not generate EVPN route type 5 updates for that IP-VRF, so option A is consistent. The ARP cache in the IP-VRF is normally required for local subnet host resolution; remote host reachability can be learned through EVPN rather than requiring every remote ARP entry to be learned by local data-plane ARP. Option B is false because ARP/GARP snooping is not performed by the IRB interface in the manner stated. ARP/GARP learning for proxy ARP and MAC/IP advertisement is associated with the MAC-VRF bridge-domain behavior and the local access side, not with the IRB subinterface indiscriminately snooping all ARP/GARP messages as described. Reference: EVPN IRB operation, RT-2 host MAC/IP advertisement, RT-5 behavior, ARP/GARP learning scope.

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Comprehensive and Detailed 150 to 250 words of Explanation From [SR Linux EVPN and Data Center Interconnect/Course Guide/topics]:

In an integrated gateway-based DCI solution, the data center gateway and WAN PE functions reside on the same router. This device acts as the interworking point between the data center EVPN/VXLAN environment and the WAN transport service. It may need to translate or interwork between VXLAN encapsulation in the data center and MPLS or another WAN tunneling protocol in the WAN. For Layer 3 services, the integrated gateway may also re-advertise EVPN routes learned from the data center fabric into VPN-IPv4 or VPN-IPv6 routes for transport across the WAN. Option B does not describe the integrated gateway model. A border leaf using eBGP or static routes to interconnect with a gateway is a decoupled gateway-based design, where the data center border leaf and WAN PE/gateway are separate devices with a routing handoff between them. In the integrated model, that border-leaf-to-separate-gateway handoff is not the defining architecture because the gateway and WAN PE roles are combined on one router. Reference: integrated gateway DCI, VXLAN-to-WAN interworking, EVPN to VPN-IPv4/VPN-IPv6 re-advertisement, decoupled gateway distinction.

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Comprehensive and Detailed 150 to 250 words of Explanation From [SR Linux EVPN and Data Center Interconnect/Course Guide/topics] :

In a single-active EVPN multi-homing design, the connected PE routers perform Designated Forwarder election to determine which PE is active for the relevant service or Ethernet Segment. The DF is responsible for forwarding toward the attached segment and, in a Layer 3 multi-homing case, only the active/DF PE advertises the customer IP prefix route toward the EVPN control plane. Single-active redundancy is communicated using Ethernet Segment-related EVPN procedures, including Ethernet A-D information, so remote PEs can identify the redundancy behavior and avoid forwarding traffic to an inactive attachment. The false statement is that the elected DF uses an AD per EVI update to identify itself as primary. AD per EVI is primarily used to advertise per-service Ethernet Segment reachability and support aliasing/load-balancing behavior in multi-homed services. DF election itself is driven by Ethernet Segment route procedures, not by the DF declaring itself primary through AD per EVI. Therefore, option B misstates the role of AD per EVI in the single-active L3 multi-homing control plane. Reference: EVPN DF election, single-active multi-homing, Ethernet A-D routes.

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