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

As a STUN server, Cisco vBond allows Cisco Catalyst SD-WAN routers to discover their public mapped IP addresses and ports when they sit behind NAT. This function is essential during overlay bring-up because many WAN Edge devices are deployed behind internet circuits, firewalls, or provider NAT devices. vBond helps devices understand how they are seen from the public transport side and facilitates the formation of secure control connections to the SD-WAN controllers. vBond also participates in orchestration and Zero-Touch Provisioning workflows, but the question specifically asks about its purpose as a Session Traversal Utilities for NAT server. That wording points directly to NAT discovery, not general ZTP. vBond does not secure user data traffic between edge routers; data-plane encryption is established between WAN Edge devices. It also has no role in integrating SD-Access wireless into a fabric. Reference topics: Cisco SD-WAN vBond, STUN, NAT traversal, orchestration, WAN Edge onboarding. This is fundamental for internet transports.

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.

An inbound IP prefix list is the correct tool because the routers must decide which prefixes to accept from the service provider based only on prefix length. Prefix lists are designed to match network prefixes and mask-length ranges using operators such as le and ge. Applying the prefix list inbound to the BGP neighbors prevents routes with masks longer than /24 from entering the local BGP table, regardless of what the service provider advertises. This conserves memory and ensures the customer routing policy is enforced locally. An access list is a poor fit because it does not natively express prefix-length logic as cleanly as a prefix list. Applying the policy outbound would filter routes the customer sends to the provider, which is the wrong direction; the requirement is about routes the customer learns. A route map could reference a prefix list, but the simplest and most exact answer is to use an IP prefix list inbound. Therefore, the design should apply an inbound prefix list to both BGP peers to block prefixes greater than /24. Reference topics: BGP route filtering, prefix lists, inbound policy, maximum accepted prefix length.