Pass the Juniper JNCIS-MistAI JN0-460 Questions and answers with CertsForce

In Juniper’scampus fabric architectures, the location of theLayer 3 gateway(IRB) differentiates between CRB and ERB models:

Centrally-Routed Bridging (CRB):L3 gateways are placed at thecore layer.

Edge-Routed Bridging (ERB):L3 gateways are placed at thedistribution layer, closer to the edge.

“In the ERB model, Layer 2 gateways are deployed at the access layer, andLayer 3 gateways are deployed at the distribution layer.”

Option A (CRB):Incorrect — L3 is at the core, not distribution.

Option B (IP Clos):Incorrect — in 3-stage Clos, L3 is pushed to the access layer.

Option D (EVPN multihoming):Incorrect — this is about redundancy, not gateway placement.

Option C (ERB):Correct — L3 gateways sit at thedistribution layerin the ERB architecture.

According to Juniper documentation, a route distinguisher (RD) is a critical address qualifier used to ensure that network layer reachability information (NLRI) remains unique within a Multiprotocol BGP (MP-BGP) control plane, especially in multitenant environments. In a service provider network, different tenants may use identical, overlapping private IP address spaces (such as 192.168.1.0/24). If these routes were advertised without a qualifier, BGP—which typically only considers the IP prefix—would treat them as the same route and potentially overwrite one with the other based on standard BGP best-path selection.

The route distinguisher solves this by prepending an 8-byte field to the tenant's IP address, effectively transforming a 32-bit IPv4 prefix into a unique 96-bit VPN-IPv4 address. This 8-byte value is typically configured in formats such as as-number:number or ip-address:number. Because the resulting VPN-IPv4 prefix is unique to that specific routing instance, the service provider's BGP infrastructure can carry and distinguish between overlapping routes from multiple customers simultaneously.

It is important to differentiate the RD from a route target (RT). While the RD's sole purpose is to provide uniqueness so that routes are not discarded or overwritten, the route target is an extended community attribute used to control the import and export of these routes into the correct virtual routing and forwarding (VRF) tables on remote PE routers. In Juniper's Junos OS, each routing instance of type vrf or evpn must have a unique RD associated with it; failing to configure a unique RD or attempting to use the same RD across different instances will result in a configuration commit failure. This fundamental separation of "making routes unique" (RD) and "directing routes to the right place" (RT) allows for the scalable, isolated multitenancy required in modern EVPN-VXLAN campus and data center fabrics.

When a switch is successfully onboarded into Mist Cloud but shows“Unassigned,”it means the device has been claimed into the organization but hasnot yet been assigned to a specific site.

“After claiming switches into an organization, you must assign each switch to a site for it to transition from Unassigned to Connected state and begin receiving configuration and telemetry updates.”

Option A:Incorrect — rescanning is not needed once the device is claimed.

Option B:Incorrect — reboots are unnecessary for assignment recognition.

Option C:Incorrect — these commands are for connectivity troubleshooting, not site assignment.

Option D:Correct— assigning each switch to itsintended siteenables full Mist management and connectivity state.

According to Juniper Mist documentation, the brownfield adoption process is utilized when bringing existing Juniper switches—which already have a local configuration—under the management of the Mist cloud. This process differs significantly from the greenfield "claiming" method, as it requires manual interaction with the device's management interface to establish the initial connection2.

A critical requirement for this process is that CLI access to the Juniper cloud-ready switch is required3. To initiate adoption, the administrator must log in to the switch via console or SSH and enter a specific set of Junos OS configuration commands provided by the Mist portal. These commands include the necessary parameters for the switch to establish an outbound SSH connection to the Mist cloud, typically using either TCP port 2200 or 443. Without direct CLI access to paste and execute these adoption strings, the switch cannot register itself with the organization's inventory in the dashboard.

Furthermore, because this process involves modifying the switch's local configuration file to add the Mist management parameters, you must perform a commit on the switch after adding the switch adoption commands7. In the Junos operating system, configuration changes reside in a candidate configuration buffer and do not take effect until a commit operation is successfully executed8. Once committed, the switch initiates the connection to Mist9. If the connection is successful, the switch status in the Mist dashboard will transition from "Unassigned" to "Connected," enabling AI-driven telemetry collection and Wired Assurance monitoring. This adoption method allows for a seamless transition of legacy infrastructure into a modern, cloud-managed environment without requiring a factory reset or the presence of a physical QR claim code.

Abrownfield adoptionin Mist AI refers to onboarding existing Juniper switches (with existing configurations) into the Mist Cloud for management and monitoring. For the switch to connect successfully, it must be able to reach Mist Cloud services usingDNSandInternet connectivity.

“To onboard existing (brownfield) switches into Mist Cloud, the device must have outbound Internet connectivity and DNS resolution to discover Mist Cloud service endpoints.”

Option A:Correct— DNS is required for the switch to resolve Mist Cloud URLs.

Option B:Correct— Internet access is required for registration and telemetry exchange.

Option C:Incorrect — templates can be applied later but are not required for adoption.

Option D:Incorrect — Mist uses TCP ports 2200 or 443, not UDP 1280.

According to Juniper Networks' validated designs for campus fabrics, the campus fabric core-distribution with edge-routed bridging (ERB) is the optimal architecture when high volumes of east-west traffic are present and access switches are restricted to Layer 2 operations. In an ERB design, the EVPN-VXLAN fabric extends from the core switches to the distribution switches.1 The critical differentiator is the placement of the default gateways (Integrated Routing and Bridging or IRB interfaces). In the ERB model, these gateways are moved from the core to the distribution layer, which effectively acts as the "edge" of the EVPN fabric.

By placing the Layer 3 gateways at the distribution layer, inter-VLAN (east-west) traffic is routed closer to the endpoints.2 This prevents the "hairpinning" effect found in Centrally-Routed Bridging (CRB) architectures, where traffic must travel all the way to the core layer to be routed between subnets before returning down to the distribution and access layers. This reduction in latency and core-link utilization is essential for modern campus environments with high server-to-server or client-to-client traffic patterns.

Furthermore, this architecture specifically accommodates Layer 2 access switches. In the ERB core-distribution model, the access switches are not part of the EVPN-VXLAN overlay; instead, they connect to the distribution tier using standard Link Aggregation Control Protocol (LACP) or ESI-LAG. This allows organizations to leverage existing legacy or lower-tier access switches that do not support advanced VXLAN capabilities while still benefiting from a robust, scalable EVPN-VXLAN fabric at the distribution and core layers.5 In contrast, while the campus fabric IP Clos also excels at handling east-west traffic, it requires the access switches themselves to perform VXLAN encapsulation/decapsulation (acting as VTEPs), which contradicts the requirement for access switches to operate only at Layer 2.

Juniper Mist supports ahierarchical configuration model:

Organization level:global configuration templates applied across sites.

Site level:shared configuration for all devices in a site.

Individual device level:unique overrides.

To applycommon system-level settings(e.g., NTP, SNMP, DNS, syslog) across multiple sites, the correct method is to use anorganization-level template.

“Organization-level templates provide a consistent configuration framework that can be applied across multiple sites, ensuring uniform system settings for all switches.”

Option A:Incorrect — manual CLI configuration defeats automation.

Option B:Incorrect — applies only to one site, not multiple.

Option C:Correct— organization-level templates provide centralized configuration for all sites.

Option D:Incorrect — individual configuration is for unique settings only.

InMist Cloud,site variablesare used to store and reference common configuration values (such as VLAN IDs, subnet addresses, or gateway IPs) that are reused across multiple devices and templates within a site.

“Site variables allow administrators to define reusable configuration parameters that can be referenced in multiple templates or device configurations, ensuring consistency and reducing manual errors.”

Option A:Incorrect — applies configuration directly, not reusable references.

Option B:Correct— site variables enable you to reference the same VLAN or value in multiple configurations (switches, WLANs, etc.).

Option C:Incorrect — WLAN templates are for wireless SSID configuration.

Option D:Incorrect — switch templates define static configuration but don’t store shared variables.

Aport negotiation mismatchoccurs when the local and remote interfaces fail to agree on common speed or duplex settings.

Marvis Wired Assurance automatically detects this by analyzing telemetry from the switch’s physical interfaces.

You can resolve this by ensuringauto-negotiationis enabled on both ends (A) and verifying the peer device supports the802.3 autonegotiation standard(D).

Manually forcing half-duplex or replacing hardware is unnecessary unless the hardware is faulty.

“Marvis Wired Actions correlate interface negotiation errors with LLDP neighbor data to pinpoint mismatched configurations, helping administrators quickly verify speed/duplex compatibility and 802.3 autonegotiation support.”

Marvis is Juniper’s Virtual Network Assistant (VNA) that leverages AI to provide natural language queries, anomaly detection, and proactive troubleshooting across wireless, wired, and WAN networks.

“Marvis, the AI-driven Virtual Network Assistant, requires a Virtual Network Assistant subscription. The subscription enables Marvis to provide insights, recommendations, and natural language queries for Mist-managed networks.”

Option A (Access Assurance) is related to NAC/802.1X enforcement.

Option B (IoT Assurance) applies to profiling and securing IoT devices.

Option D (Wired Assurance) enables switch telemetry, onboarding, and assurance, but does not unlock Marvis.

Option C (Virtual Network Assistant) is correct — this subscription is required to enable Marvis AI.