ADMIN, FABRIC and GREEN map onto Microsoft's Enterprise Access model. An asset's zone is the highest tier it can control — so a server's BMC lives with the identity it could seize.
Identity and anything that can seize it.
The control planes that run everything.
Users, apps, and every AI agent.
A higher zone is never administered from a lower one; credentials never flow downward. Admin is reached only from a dedicated Privileged Access Workstation, just-in-time, with a phishing-resistant key.