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

The selected design is correct because the requirement describes a resilient campus architecture that must support the same VXLAN at any access-layer switch while maintaining fast convergence and high availability. In Cisco campus and data-center-style fabric designs, VXLAN provides network virtualization by carrying Layer 2 adjacency over a routed or resilient transport. The correct design must avoid a fragile single spanning-tree domain and must provide redundant forwarding paths so that an access switch or uplink failure does not isolate the VLAN or VXLAN segment. The selected option represents the design that meets those conditions by allowing the overlay segment to be extended consistently across access switches while keeping the underlay resilient. Designs that rely on a traditional Layer 2 tree, a single aggregation point, or blocked redundant links would not meet the high availability and fast convergence objectives. The important design principle is that VXLAN should ride on a stable, redundant transport and should not depend on large Layer 2 failure domains. Reference topics: VXLAN campus design, overlay networking, fast convergence, access-layer resiliency, high availability.

The configuration-protocol mapping distinguishes NETCONF and RESTCONF behavior in model-driven programmability. NETCONF is an XML-based network configuration protocol that runs over a secure transport such as SSH and supports structured operations such as get-config, edit-config, lock, unlock, commit, and datastore manipulation. It is well suited to transactional configuration workflows where candidate and running datastores are supported. RESTCONF exposes YANG-modeled data through a REST-style interface over HTTP or HTTPS, using familiar methods such as GET, POST, PUT, PATCH, and DELETE. It can encode data in XML or JSON depending on headers and implementation. Both protocols use YANG models to define the structure and semantics of configuration and operational data, but they differ in transport style, operation model, and tooling. The selected mapping therefore places NETCONF characteristics with the protocol that provides RPC-style operations and datastore handling, while RESTCONF receives HTTP method and URI-based characteristics. In design, the choice depends on controller support, device operating system, required transaction semantics, security policy, and developer tooling. Reference topics: NETCONF, RESTCONF, YANG, datastores, XML and JSON encoding.

VRRP object tracking allows the effective priority of a VRRP router to change when a tracked object changes state. Cisco documentation states that VRRP object tracking ensures the best VRRP router is master by altering VRRP priorities according to tracked objects such as interface or IP route states. This directly supports answer A. It also supports answer D, because VRRP can track interfaces and routes through the tracking process. The priority does not have to remain fixed; object tracking is specifically designed so a router can lower its priority when an uplink, route, or critical dependency fails. A VRRP group is not limited to one tracked object in modern Cisco implementations, so option C is too restrictive. VRRP does not support only interface tracking; route tracking is also a common use case, especially when the LAN interface is still up but upstream reachability has failed. In a resilient campus or branch gateway design, object tracking prevents a router from remaining master when it no longer has a valid upstream path, improving deterministic failover.