4A0-D03 Exam Dumps - Nokia Certified Data Center Fabric Professional Questions and Answers

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

In interface-less symmetric routing, the EVPN fabric exchanges host forwarding information using EVPN route type 2 MAC/IP advertisements. RT-2 carries the host MAC address and, when present, the associated host IP address, allowing remote PEs to build the forwarding state needed for distributed gateway operation. Unlike asymmetric routing, interface-less symmetric routing does not require every MAC-VRF to be instantiated on every PE. The design scales better because each leaf only needs the locally attached MAC-VRFs plus the shared IP-VRF/routed VXLAN construct for inter-subnet forwarding. Option B describes an asymmetric forwarding pattern more than a symmetric one; in symmetric routing, both ingress and egress PEs perform routed forwarding functions through the IP-VRF. Option C is also incorrect because anycast gateway is fundamental when multiple leaves provide the same default-gateway service for a subnet. Therefore, the true statement is that forwarding information is exchanged using EVPN route type 2 updates. Reference: interface-less symmetric routing, EVPN RT-2 host MAC/IP signaling, distributed IRB operation.

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

This setup represents a Layer 2 EVPN multi-homing attachment where the host is connected to Leaf1 and Leaf2 through an Ethernet Segment named ES-1. In SR Linux EVPN multi-homing, the Ethernet Segment must be associated with the physical or logical attachment interfaces facing the host. This allows the PEs to advertise Ethernet Segment information into EVPN, participate in DF election, and apply the appropriate forwarding behavior for single-active or all-active redundancy. Option D is therefore correct. Option A is not necessarily true because the exhibit indicates an active/standby style attachment, not all-active operation. Option B is also incorrect because ECMP on the remote MAC-VRF is not the mechanism that defines the local ES association or single-active behavior. Option C is wrong in this setup because a host LAG is required for common all-active L2 multi-homing with LACP, but the shown design uses an active/standby-style attachment where the Ethernet Segment is bound to the host-facing ports. The technical anchor is that ES-1 must be associated to the access ports connecting the host into the multi-homed MAC-VRF service. Reference: L2 EVPN multi-homing, Ethernet Segment interface association, DF behavior.

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

An IRB interface provides the logical L3 gateway function between a Layer 2 MAC-VRF and a Layer 3 IP-VRF on the same PE. It allows locally bridged hosts to route into the tenant IP-VRF while preserving EVPN control-plane signaling for MAC/IP reachability. The IRB subinterface must have at least one IP address because it acts as the routed gateway for the subnet, and it may also be configured with ACLs to apply traffic policy at the L3 boundary. Option B is false because it incorrectly generalizes the IRB relationship. In SR Linux EVPN service modeling, an IRB subinterface connects a MAC-VRF to an IP-VRF in a controlled one-to-one service attachment context; the design is not that both IP-VRFs and MAC-VRFs arbitrarily contain multiple IRB interfaces for the same relationship. A MAC-VRF has its IRB gateway association into the IP-VRF, and the IP-VRF may connect to multiple MAC-VRFs through distinct IRB contexts, but the statement as written is not the correct rule for IRB interface behavior. Reference: SR Linux IRB interface operation, MAC-VRF/IP-VRF interconnection, gateway IP and ACL support.

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

Layer 3 multi-homing is fundamentally about redundant or load-balanced L3 reachability for external prefixes, not about Layer 2 broadcast-domain flooding toward a host. In single-active L3 multi-homing, DF election determines which attached leaf is active for the Ethernet Segment, and only that leaf advertises or forwards for the attached customer route as required by the redundancy model. In all-active L3 multi-homing, multiple leaf routers can be valid next-hops for the same learned third-party prefix, and remote PEs may load-balance toward them based on the Ethernet Segment association. Learned external prefixes are carried as EVPN route type 5 IP Prefix routes, which is the correct route type for L3 reachability. The Ethernet Segment is associated with the next-hop for those prefixes so that remote PEs understand the multi-homed nature of the path. Option B is false because BUM forwarding is a Layer 2 EVPN concern. In an all-active L3 multi-homing scenario, DF election is not used to identify a BUM-forwarding leaf for host traffic in the same way it is used in Layer 2 multi-homing services. Reference: L3 EVPN multi-homing, RT-5 prefix routes, ES next-hop behavior.

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

An anycast-gateway IRB allows multiple PEs to present the same default-gateway IP address to hosts in the same subnet. This is the mechanism that enables distributed gateway behavior in EVPN fabrics. The same anycast gateway IP may be configured on equivalent IRB subinterfaces across remote PEs participating in the same IP-VRF, allowing hosts to use the nearest leaf as their default gateway without changing their gateway address. SR Linux also associates gateway MAC information with the IRB, including virtual gateway MAC behavior used inside the MAC-VRF forwarding table. Option C is false because the anycast gateway IP is not treated as a normal unique host route that appears in the IP-VRF route table alongside the subnet prefix. The subnet route is installed for the connected network, but the shared anycast gateway address is a gateway function, not a separately advertised host endpoint that should appear as ordinary routed host reachability. Treating the anycast IP as a regular host route would undermine the distributed gateway model and create ambiguous ownership across PEs. Reference: IRB anycast gateway, MAC-VRF/IP-VRF interconnection, distributed default-gateway operation.

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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 routes are EVPN route type 1 advertisements used in multi-homing at the service-instance level. A PE sends an AD per EVI route for each MAC-VRF associated with the Ethernet Segment. These routes allow remote PEs to understand that the advertising PE has reachability to a given EVI through the shared ES. They are also used for aliasing and fast convergence, because a remote PE can treat multiple attached PEs as valid paths for traffic toward the same multihomed segment. In VXLAN EVPN, the update can include data-plane information such as the VNI, and it carries route-target information so the route is imported into the correct MAC-VRF. Option B is false because the multi-homing type or redundancy mode is not carried in the AD per EVI update as stated. Redundancy behavior is associated with Ethernet Segment-level signaling and configuration, especially ES discovery and related route attributes, not with AD per EVI as the mechanism that declares the multi-homing type. Reference: EVPN RT-1 AD per EVI, MAC-VRF association, route target, VNI, aliasing.

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