In Juniper Mist campus fabric architectures, thelocation of the Layer 3 gateway (IRB interface) differentiatescentrally-routed bridging (CRB)fromedge-routed bridging (ERB):
InCRB, thegateway resides at the core layer- routing occurs centrally, and access/distribution layers perform Layer 2 bridging.
InERB, thegateway moves to the edge (distribution layer), enabling routing to occur closer to endpoints, improving performance and scalability.
"In a centrally-routed bridging (CRB) topology, Layer 3 gateways reside at the core. When transitioning to an edge-routed bridging (ERB) design, the Layer 3 gateways are moved to the distribution layer, closer to the access switches and clients." Therefore, when moving from acore-distribution CRBto anERBmodel, thegateway moves from the distribution to the access layerin campus terms (edge = access).
Option A:Incorrect - ERB gateways are not at the distribution layer only.
Option B:Incorrect - opposite direction.
Option C:Correct- the gateway movesfrom distribution to access (edge).
Option D:Incorrect - this describes CRB, not ERB.
References:
Juniper Mist AI for Wired - Campus Fabric Architecture Models (CRB vs ERB) Juniper Validated Design - Campus Fabric EVPN-VXLAN Gateway Placement Junos OS EVPN-VXLAN Deployment Guide

Marvis, the AI-driven virtual network assistant in Mist, provides real-time troubleshooting insights for both wired and wireless devices.
When used withWired Assurance, certain actions require Juniper EX or QFX switches for telemetry collection.
Two of these wired-specific actions are:
Bad Cable Detection- triggered when electrical faults or poor cable quality are observed through LLDP or physical diagnostics.
References:Juniper Mist Marvis Wired Assurance Overview