Configuration Management Database

Discovery exists to populate a healthy CMDB. This domain is about how data lands correctly and stays trustworthy.

CI classes and the CMDB

• CIs live in class tables that extend a base class (cmdb_ci) in a hierarchy (e.g., cmdb_ci_server → cmdb_ci_win_server). A more specific subclass inherits the parent's fields.
• Classification during Discovery determines which class a CI is written to; reclassification moves a CI from one class to another (for example, when a device was first found generically and later identified more precisely). Reclassification can be switched (downgrade/upgrade within the hierarchy).

Identification and Reconciliation Engine (IRE)

The IRE is the single gateway through which Discovery (and other sources) write CIs, so the CMDB stays free of duplicates.

• Identification rules — each CI class has an identification rule made of one or more identifier entries, evaluated in priority order. An entry lists the criterion attributes that must match an existing CI for it to be considered "the same." Example: a server may be identified by serial number first, then by name + IP.
• Reconciliation rules — when multiple discovery sources can write the same attribute, reconciliation decides which source is authoritative for that attribute, preventing one source from overwriting another's better data.
• Data sources & precedence — IRE tracks which source last updated a CI; this underpins reconciliation and helps spot conflicting writes.
• IRE applies to payloads (including those from Discovery patterns and Import Sets), inserting, updating, or matching CIs as the rules dictate.

CMDB Health

CMDB Health dashboards score data quality across KPIs grouped into three families you should memorize:

• Completeness — are required attributes and required relationships populated? (e.g., CIs missing an owner or a critical attribute).
• Compliance — do CIs follow expected rules: correct class, no orphans, no stale records (not updated within an expected window), duplicates flagged.
• Correctness — are values valid and consistent (e.g., duplicate detection, recommended attribute values).

Health jobs run on a schedule and feed dashboards used to prioritize remediation (deduplicate, fill gaps, retire stale CIs).

What to drill for Domain 3: the CI class hierarchy and reclassification; that IRE is the mandatory entry point preventing duplicates; identifier entries with criterion attributes evaluated by priority; reconciliation deciding authoritative source per attribute; and the three CMDB Health families (completeness, compliance, correctness) plus what staleness/duplicates mean.