Pass the Cisco CCNP Enterprise 350-401 Questions and answers with CertsForce

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The correct answer is D.

Cisco campus design guidance explains that a nonlooped topology with unique VLANs per access switch improves stability and convergence compared with looped Layer 2 designs. Cisco states that in a multilayer campus design, each access switch should have unique VLANs, with no Layer 2 loops and no blocked links, which improves convergence behavior. Cisco also notes that VLANs spanning multiple access switches increase flooding impact, while a nonlooped topology with localized VLANs reduces that impact.

A traditional nonlooped design reduces reliance on spanning-tree reconvergence across shared Layer 2 domains. With unique/local VLANs, failures affect a smaller fault domain and convergence is faster than in a looped design with common VLANs stretched across switches. Cisco’s campus design material specifically recommends no Layer 2 loops and unique VLANs per access switch for better operational behavior.

A. Traditional looped design that has common VLANs extended between separate access switches This increases Layer 2 complexity and spanning-tree dependency, which slows convergence compared to a nonlooped design. Cisco documents that VLANs spanning multiple access switches increase flooding impact.

B. Cisco SD-Access configuration between aggregation intermediate nodes and access layers This is not the standard way the question is framed for classic aggregation-to-Layer 2 access convergence in a traditional enterprise campus design. The question is targeting the design principle of looped vs nonlooped Layer 2 access.

C. Cisco SD-Access configuration between aggregation and access-layer edge nodes SD-Access is a different fabric architecture. The question is about reducing convergence time between aggregation and a Layer 2 access layer, which maps to the traditional campus design choice rather than SD-Access node roles.

For enterprise campus design, remember:

Looped Layer 2 + stretched/common VLANs = slower convergence and larger fault domains

Nonlooped Layer 2 + unique/local VLANs per access switch = faster convergence and better stability

The Python library commonly used for NETCONF automation is ncclient. NETCONF is an XML-based network management protocol that uses YANG data models to structure configuration and operational state. The ncclient library provides Python functions for connecting to NETCONF-capable devices, opening a manager session, issuing get, get-config, edit-config, and other NETCONF operations, and processing XML responses. Option A is correct. The requests library is commonly used for REST API calls over HTTP or HTTPS, such as RESTCONF or controller northbound APIs, but it is not the standard NETCONF client library. Postman is an API testing application, not a Python library. cURL is a command-line tool for sending HTTP and other protocol requests, not a Python library for NETCONF/YANG workflows. In ENCOR automation, the distinction matters: REST-based APIs often use JSON and HTTP methods, while NETCONF uses XML-based RPC operations over SSH and is commonly automated in Python with ncclient. References/topics: ENCOR Automation, NETCONF, YANG, Python automation, ncclient, model-driven programmability.

The correct answer is C. using BFD.

In Cisco Catalyst SD-WAN, the health of data plane tunnels is monitored using Bidirectional Forwarding Detection (BFD). Cisco documentation states that BFD runs over all data plane tunnels between Cisco IOS XE Catalyst SD-WAN devices and is used to monitor the liveness and path characteristics of those tunnels, including loss, jitter, and latency.

BFD is the protocol specifically used in Cisco SD-WAN to detect tunnel failures quickly and measure tunnel quality. These measurements are also used by SD-WAN features such as application-aware routing to make path-selection decisions.

A. with IP SLA IP SLA is a Cisco feature for measuring network performance in many environments, but Cisco SD-WAN data plane tunnel health is monitored with BFD, not IP SLA.

B. with OMP OMP (Overlay Management Protocol) is the control-plane routing protocol in Cisco SD-WAN. It distributes routes, TLOCs, and service information, but it does not monitor data plane tunnel health.

D. ARP probing ARP is used for Layer 2/neighbor resolution on local segments and is not the tunnel-health monitoring mechanism for SD-WAN data plane tunnels.

ENCOR exam point:

In Cisco Catalyst SD-WAN:

OMP = control-plane route exchange

BFD = data-plane tunnel liveliness and performance monitoring

Auto-RP is used in Protocol Independent Multicast sparse-mode environments to distribute rendezvous point information automatically. In PIM sparse mode, multicast routers must know which RP is responsible for specific multicast group ranges. Without a dynamic RP-discovery mechanism, administrators would have to configure RP information manually across routers. Auto-RP solves that by allowing candidate RPs to announce themselves and mapping agents to advertise group-to-RP mappings throughout the multicast domain. Therefore, option B is correct. Option A is incorrect because Auto-RP does not distribute IGMP traffic; IGMP operates between hosts and local multicast routers to manage group membership. Option C is wrong because Auto-RP does not automate leaf-router configuration generally; it specifically distributes RP mapping information. Option D is also inaccurate because Auto-RP does not perform an election in the same way as BSR. It advertises candidate RP and mapping-agent information so routers can learn RP mappings. The key ENCOR concept is multicast control-plane discovery for PIM sparse-mode RP selection. References/topics: ENCOR multicast, PIM sparse mode, Auto-RP, rendezvous point discovery, multicast group-to-RP mapping.