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

This YANG mapping is based on how IETF, OpenConfig, and Cisco native models differ in portability and schema organization. IETF models are produced through the standards process and are appropriate when the same management structure is expected across vendors for common protocols. OpenConfig models are also vendor-neutral, but they are built around a consistent operational model used heavily for streaming telemetry and multivendor automation. Cisco native models mirror Cisco platform configuration more closely and expose device-specific capabilities that may not exist in common models. The selected answers keep those boundaries clear. This matters because a NETCONF or RESTCONF payload is validated against the YANG schema; a payload written for one model family cannot be assumed to work against another. In design terms, the model family should be selected after confirming device software release support, feature coverage, operational-state requirements, and vendor diversity. Open models give portability; native models give feature completeness. Reference topics: IETF YANG, OpenConfig YANG, Cisco native YANG, schema validation, automation model selection.

In a Cisco SD-Access fabric, DHCP relay design must account for the fact that endpoints can attach to different fabric edge nodes while using consistent anycast gateway behavior. DHCP Option 82 is important because it inserts relay-agent information that allows the DHCP infrastructure to identify where the DHCP request originated. This enables the correct address scope and policy context to be selected for the endpoint even when the gateway address is anycast across multiple fabric edges. Cisco SD-Access DHCP guidance emphasizes the use of relay information so centralized DHCP services can assign the correct address based on fabric location and endpoint context. DHCP relay is not simply enabled on border nodes, and subnets should not be stretched across fabric edges by placing DHCP servers on borders. DHCP servers do not require a special proprietary SD-Access extension in the sense described by the incorrect option; they use standard relay information such as Option 82. Therefore, the key design consideration is enabling DHCP Option 82 so the circuit information maps the request to the fabric node where it originated.

Explicit QoS trust should be configured at the network boundary points where markings first enter the managed DiffServ domain and are known to be reliable. In a DiffServ design, traffic classification and marking are typically performed at the access edge or at a controlled ingress boundary, and downstream devices then honor DSCP or CoS markings based on the trust boundary. Cisco QoS design stresses that the trust boundary must be intentionally placed; endpoints or unmanaged devices should not be trusted by default because they can mark traffic incorrectly and steal priority treatment. The exhibit answer identifies B and E as the correct trust points, meaning those are the controlled ingress locations where markings should be accepted. Options that trust uncontrolled endpoint-facing points or internal transit locations would either create a security problem or add no practical value. Once traffic is trusted and marked at the correct boundary, queuing, policing, and shaping policies can use the DSCP values consistently across the campus or WAN. Reference topics: DiffServ, QoS trust boundary, DSCP marking, classification, enterprise QoS design.