CIS-DF--Day11- IRE - Identification Rule - Types

1. Overview of the IRE (Identification & Reconciliation Engine) IRE determines whether to update an existing CI or create a new one by checking fields like: Serial Number Name MAC Address Other identifiers (based on class) If no match is found → a new CI is created. 2. Types of CI Classes Every CI class in ServiceNow falls into either: Hardware Application Each class inherits default identification rules from its parent (hardware/app). 3. Identification Rules Identification rules ensure: Data integrity Avoidance of duplicate CIs Consistency Improved data quality They define how a CI is uniquely identified. Two Types of Identification Rules Independent Identifies CI only using its own attributes Faster and recommended Dependent Identification depends on another CI and its relationship Slower; not recommended Example analogy: Independent = travelling alone Dependent = waiting for someone else before travelling 4. Creating a Custom CI Class Steps covered: Add child class under cmdb_ci_computer Add attributes (fields) Set identification rule Choose rule type (independent/dependent) Configure lookup tables if needed Lookup Tables Used when CI info needs to be verified from another table (e.g., Asset table). Still independent, just referencing other data. 5. Duplicate CI vs Overloaded CI Duplicate CI Same CI represented multiple times in CMDB. Occurs when identification rules are weak. Overloaded CI Multiple different CIs being treated as one CI. Example: All fruits identified as “Lemon”. Occurs due to bad rules or multi‑source mismatches. 6. Multi‑Source Discovery Why do we need multiple sources (e.g., SCCM, Intune, Discovery, Monitoring tools)? Some tools don’t discover all device types User devices often not discovered by ServiceNow Discovery Network devices monitored via specialized tools Multiple sources bring different data attributes To get full infrastructure coverage 7. Reconciliation Rules (Brief Introduction) Reconciliation determines: Which source’s data should be trusted Which attribute values override others when conflicts occur Example: One source reports RAM = 16GB, another says 32GB → reconciliation rule decides which wins. Full topic to be covered in the next session. 8. Key Takeaways Independent rules are preferred. CI classes rarely need to be created; ServiceNow provides 900+ classes. Lookup helps reference other tables but keeps the rule independent. Upgrade impact is minimal for custom classes unless ServiceNow introduces the same class. Multi-source always demands reconciliation rules. IRE is available even without Discovery plugin, but multi-source property may need enabling.