300-420 Exam Dumps : Designing Cisco Enterprise Networks (ENSLD) v1.1

Route summarization should be planned from the aggregation layer toward both the core and the access layer. In hierarchical campus routing, aggregation or distribution devices are natural summarization boundaries because they sit between more specific access-layer networks and the core. Summarizing from aggregation toward the core prevents access-layer subnet churn from forcing unnecessary recomputation and route table growth in the core. Summarizing from aggregation toward access can also provide a concise upstream route, often a default or summary route, so access devices do not need the entire network routing table. The goal is to contain failures, reduce routing state, and preserve fast convergence at hierarchy boundaries. Summarizing from the core toward aggregation may hide useful topology details in the wrong direction, while summarizing directly from access toward aggregation is not always possible or efficient when access devices are numerous and have limited resources. The answer that places summarization at aggregation in both directions best matches Cisco hierarchical design principles. Reference topics: hierarchical campus design, route summarization, aggregation layer, core route scale, convergence containment.

Redundancy for Cisco vBond Orchestrators is normally achieved by mapping the IP addresses of multiple vBond instances to a single DNS name. WAN Edge devices use the configured organization name and vBond DNS name during onboarding to resolve and contact an available orchestrator. This design allows several vBond nodes to be deployed across different locations or availability zones while giving the edge device a consistent bootstrap target. If one vBond is unavailable, DNS resolution can return another reachable vBond address, allowing control-connection orchestration to continue. Selecting only the closest vBond is not the redundancy mechanism described here, and deploying a single vBond creates an avoidable single point of failure. The answer that says WAN Edge routers are configured with all orchestrators by IP address and priority does not represent the common DNS-based design model. In production, the DNS record, certificates, firewall policy, NAT behavior, and controller reachability should all be validated so that WAN Edge devices can reach multiple vBond instances during onboarding and after failures. Reference topics: Cisco SD-WAN controller redundancy, vBond DNS, device onboarding, orchestration availability.

Route summarization and EIGRP stub routing are the two correct design techniques for a stable and scalable EIGRP deployment. Summarization reduces the number of prefixes advertised upstream, conserves bandwidth and memory, hides route flaps behind the summary boundary, and reduces the size of the EIGRP topology table. Stub routing prevents branch or access devices from being used as transit routers and limits the scope of EIGRP queries. This is critical because uncontrolled EIGRP query propagation can increase convergence time and processing load, especially in larger hierarchical networks. Prefix lists and distribute lists can filter routes, but filtering alone does not provide the same query-boundary and topology-hiding benefits as summarization and stubs. Static redistribution increases complexity and can create loop or policy risks if not controlled with tags and metrics. The question specifically asks to conserve bandwidth, memory, and CPU, prevent suboptimal routing, and avoid unnecessary queries; summarization and stub routing are the direct Cisco design answers. The architect should summarize at hierarchy boundaries and configure access or branch routers as EIGRP stubs where they should not provide transit. Reference topics: EIGRP summarization, EIGRP stub routing, query scope, hierarchical routing.