The on-premises directory.
WHAT IT IS
A directory service providing authentication, authorisation and configuration management for a network.
WHAT THE STRUCTURE IS
A forest, containing one or more domains Domains, containing objects Organisational units, containing objects within a domain Sites, representing physical locations
WHAT AN ORGANISATIONAL UNIT IS FOR
Grouping objects for administration and policy application.
WHAT IT IS NOT FOR
Granting permissions. Groups do that.
WHAT A DOMAIN CONTROLLER IS
A server holding a copy of the directory and authenticating users.
HOW MANY YOU NEED
At least two, in any environment that matters.
WHY
One is a single point of failure for all authentication.
WHAT REPLICATION DOES
Keeps controllers synchronised.
WHAT THE OPERATIONS ROLES ARE
Specific functions held by particular controllers.
WHY THAT MATTERS
Some operations fail if the holder is unavailable, and losing one permanently requires deliberate recovery.
WHAT TO RECORD
Which controller holds which role.
WHAT TO MONITOR
Replication health, which fails silently.
