Cisco Designing Cisco Enterprise Networks (ENSLD) v1.1 300-420 Exam Dumps: Updated Questions & Answers (June 2026)

NBAR2 should be used to identify the affected cloud applications and then allocate bandwidth according to the measured application requirements. Modern collaboration suites often use dynamic ports, encrypted sessions, and multiple flows for voice, video, messaging, file sharing, and screen sharing. Classifying them only by static ports is unreliable and can misclassify traffic, especially when applications change transport behavior or use shared cloud endpoints. Cisco NBAR2 provides application recognition beyond basic port matching and can classify traffic by application signatures. Once the applications are identified, the QoS policy can be adjusted to give the required bandwidth, priority, or queue treatment. Reserving bandwidth only on perimeter routers is incomplete if congestion occurs elsewhere in the WAN path. Rate-limiting the applications would likely make the user experience worse. The key problem is that the existing policy works for other applications but not these cloud-based tools, so the first design step is accurate application visibility and classification. NBAR2 provides that visibility and supports a more precise QoS policy. Reference topics: NBAR2, application-aware QoS, cloud collaboration traffic, DSCP classification, bandwidth allocation.

OSPF with stub areas is the correct implementation. The reference to RFC 5340 points to OSPFv3, which Cisco documents as the OSPF version used for IPv6 and also capable of carrying IPv4 unicast address families in modern implementations. OSPF is a link-state routing protocol that provides loop-free convergence through SPF calculation, making it a stronger fit than static routing or RIP for a growing WAN. Stub areas reduce routing information inside branch or regional areas by blocking external LSAs and allowing the ABR to inject a default route. That reduces route-table size and limits update propagation, which matches the requirement to optimize routing tables and reduce routing updates between routers. EIGRP with multiple autonomous systems is not aligned with RFC 5340. BGP address families are useful in provider and MPLS VPN designs but are not the best internal route-optimization answer here. OMP is specific to Cisco SD-WAN, not a generic RFC 5340 routing design. Reference topics: OSPFv3, RFC 5340, stub areas, LSA reduction, SPF convergence.

Contracting an internet connection and deploying DMVPN is the most practical solution when the enterprise needs a fast, affordable, and reliable backup for a single MPLS provider. DMVPN can use broadband internet transport to build encrypted GRE/IPsec tunnels between sites, providing a backup WAN path without waiting for another private MPLS provider circuit. It supports dynamic routing and can be deployed incrementally, which makes it suitable after a recent outage when time and cost matter. BFD echo mode toward a provider PE can improve failure detection, but it does not create an alternate transport if the only MPLS provider has an outage. Adding a WAN router and a floating static route also fails unless another path exists. Contracting a second MPLS provider and deploying GETVPN may be robust, but it is slower and more expensive than the requested quick and affordable backup. Reference topics: DMVPN backup WAN, MPLS resiliency, internet VPN, IPsec, branch availability, rapid WAN deployment.

Internal border and anywhere border are valid Cisco SD-Access border node types. A border node connects the SD-Access fabric to networks outside the fabric, but different border roles are used depending on what external reachability is required. An internal border provides connectivity to known internal networks such as shared services, data center prefixes, or enterprise routes that should be reachable from inside the fabric. An anywhere border combines external and internal border behavior and can provide broader exit capabilities depending on the fabric design. The commonly described border roles also include external border, which provides default or Internet-facing exit from the fabric, but that option is not available in the listed choices. “Extended border,” “edge border,” and “intermediate border” are not the correct named border node types. The answer is therefore internal border and anywhere border. Border placement is a major design decision because it influences route advertisement, VN-to-VRF mapping, external connectivity, transit behavior, and failure-domain boundaries for SD-Access fabrics.

A full-mesh topology best satisfies the requirement that devices make informed forwarding decisions, backup paths always exist, and suboptimal paths are used only after a failure. In a full mesh, each site or WAN node has direct connectivity to every other relevant node. This gives the routing protocol complete path visibility and allows traffic to use direct optimal paths under normal conditions. If a direct link fails, alternate paths remain available through other nodes, so the network can reroute without depending on a single hub. A hub-and-spoke design is simpler and less expensive, but spoke-to-spoke traffic must traverse the hub, which is suboptimal even during normal operation. A partial mesh can reduce cost but may still force some traffic over indirect paths when no direct connection exists. Clos is a data center fabric topology concept and is not the typical WAN topology answer here. The full mesh is the most resource-intensive design, but it best matches the stated forwarding and backup requirements. Reference topics: WAN topology, full mesh, path optimality, backup paths, routing convergence.

Cisco SD-WAN uses the Overlay Management Protocol to exchange control-plane information between WAN Edge routers and vSmart controllers. OMP advertises three major categories of routing information: OMP routes, TLOC routes, and service routes. OMP routes represent reachability to prefixes in service VPNs, such as connected, static, OSPF, EIGRP, BGP, or other routes learned at the local site. TLOC routes describe transport locations, which bind a system IP, color, and encapsulation to a WAN transport attachment. Service routes indicate service insertion capabilities, such as firewalls or other network services that can be reached through a particular site. This separation allows Cisco SD-WAN to build a secure overlay over any public or private transport while keeping transport reachability, service-side prefixes, and inserted services distinct. The other answer choices use generic terms such as underlay, MPLS, Internet, backup, or primary routes, but those are not the formal OMP advertisement categories. Therefore, the correct answer is prefix, TLOC, and service.

The SD-Access control-plane node performs the LISP Map-Server and Map-Resolver functions. Cisco SD-Access uses LISP in the control plane to maintain mappings between endpoint identifiers and routing locators. Fabric edge nodes discover local endpoints and register them with the control-plane node. When a destination endpoint is not known locally, a fabric node queries the control-plane node, which resolves the endpoint location and returns the locator information needed for VXLAN forwarding through the fabric. This is why the control-plane node is the correct answer. A fabric edge node connects endpoints, provides the anycast gateway, encapsulates and decapsulates user traffic, and registers endpoints. A border node connects the fabric to external networks. An intermediate node simply transports routed underlay traffic between fabric nodes and does not hold endpoint mappings. In design terms, control-plane placement and redundancy are critical because endpoint mobility, fabric forwarding lookup, and location resolution depend on stable Map-Server and Map-Resolver services. Reference topics: Cisco SD-Access control plane, LISP Map-Server, LISP Map-Resolver, EID-to-RLOC mapping, fabric edge registration.

Redistributing OSPF process 1 into process 2 on both R1 and R4 provides the required backup routing behavior between the management network and the target routers. The design requirements are failure driven: if R1 fails, NMS traffic must use R4, and if the link between R5 and R6 fails, traffic to 10.6.6.6 must still route through R4. When separate OSPF processes or domains exist, controlled redistribution at both exit points allows reachability to be maintained through either redistribution point. Advertising a single address into OSPF with high cost on R1 does not solve both failure cases. Static routes with IP SLA on R2 and R3 would be more manual and less aligned with the dynamic OSPF design. Default-information originate would provide a default path but would not accurately advertise the specific internal reachability required for the NMS destinations. The redistribution design must also include route filtering or tagging in production to prevent feedback loops. Reference topics: OSPF redistribution, redundant redistribution points, management reachability, route control, failure-path design.

The standards-based mechanism for dynamic rendezvous point distribution in a large PIM domain is Bootstrap Router. BSR allows candidate RPs and candidate BSRs to participate in a standards-based election and advertisement process so PIM routers can learn the RP set dynamically. This avoids configuring every router manually with static RP information and avoids depending on a Cisco-proprietary mechanism. Auto-RP can also distribute RP information dynamically, but Auto-RP is Cisco proprietary and therefore does not meet the nonproprietary requirement. Embedded RP is associated with IPv6 multicast group addressing and is not the general-purpose answer for automating RP discovery in a large IPv4 PIM domain. Static RP configuration is simple and deterministic, but it does not automate RP distribution and becomes operationally fragile as the multicast domain grows. In Cisco multicast design, BSR is the correct choice when the network requires dynamic RP discovery, vendor-neutral behavior, and scalable PIM-SM operation across a large domain.

MSTP is the correct spanning-tree choice for a Layer 2 design with many logical ports, multiple trunked VLANs, and a subsecond convergence requirement. Rapid PVST+ provides rapid convergence, but it creates a separate spanning-tree instance for every VLAN. With 30 VLANs on trunks and hundreds of active ports, the number of logical STP ports can grow quickly and increase CPU and memory load. MSTP maps many VLANs into a smaller number of spanning-tree instances while still using rapid convergence behavior based on IEEE 802.1w principles. This makes it more scalable for large Layer 2 domains than PVST+ or Rapid PVST+ when many VLANs are present. CST provides a single instance but lacks the flexibility and convergence characteristics expected in modern enterprise designs. The design needs both scalability and fast convergence, and MSTP is the standards-based protocol that best satisfies both requirements. Reference topics: MSTP, Rapid STP, logical STP ports, VLAN-to-instance mapping, Layer 2 scalability, convergence.