CMDB Identification and Reconciliation: IRE Engine and Reconciliation Rules
Which TWO statements about ServiceNow CMDB identification and reconciliation are correct?
Quick Answer
Reconciliation rules are the piece of the CMDB engine that decides which data source wins when two feeds disagree about the same CI attribute, and that is exactly why this statement is correct. Think of the CMDB as constantly receiving updates from many places at once, such as Discovery scans, Service Mapping, and third-party integrations, each of which may report a slightly different value for the same field on the same configuration item. Without a mechanism to arbitrate those conflicts, the CMDB would end up with unreliable data, overwritten unpredictably by whichever source happened to write last. Reconciliation rules solve this by assigning priority to specific sources for specific attributes, so a trusted source like Discovery might always win over a manual entry for something like operating system version. This is a different job from identification rules, which only determine whether an incoming record matches an existing CI or should create a new one; they never touch which value gets kept once a match is confirmed. Keeping these two rule types separate in your mind is the key to answering CMDB questions correctly: identification is about matching records to CIs, while reconciliation is about resolving conflicting attribute values once that CI is confirmed. Whenever a question asks about which data source takes precedence or which value survives a conflict, reconciliation rules are the mechanism being tested.
⚠ Common exam trap
Candidates often confuse the roles of identification rules (which find duplicates) with reconciliation rules (which resolve attribute conflicts), leading them to incorrectly select option C as correct.
Answer choices
Why each option matters
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
The Identification and Reconciliation (IRE) engine processes incoming CI data.
The Identification and Reconciliation (IRE) engine is the ServiceNow component responsible for processing incoming CI data from sources like Discovery, Service Mapping, or integrations. It applies identification rules to determine if a CI already exists and reconciliation rules to resolve attribute conflicts, ensuring data integrity in the CMDB.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
The 'Source' field on a CI can be set per attribute.
Why it's wrong here
Source is set at the CI level, not per attribute.
- ✓
The Identification and Reconciliation (IRE) engine processes incoming CI data.
Why this is correct
The IRE handles identification and reconciliation of CI data.
- ✗
Reconciliation rules are used to identify duplicate CIs.
Why it's wrong here
Identification rules, not reconciliation, handle duplicates.
- ✓
Reconciliation rules define which source has priority for updating CI attributes.
Why this is correct
Reconciliation rules determine source priority.
- ✗
The CMDB automatically deletes duplicate CIs when detected.
Why it's wrong here
Duplicates are flagged but not automatically deleted.
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Same concept, more angles
2 more ways this is tested on SNOW-CSA
These questions test the same concept from different angles. Work through them to make sure you can recognise it however the exam phrases it.
Variation 1. A custom table 'u_custom_server' extends 'cmdb_ci_server' and has additional fields. The admin notices that while regular attribute updates on the parent table propagate correctly to the child, some custom fields are not being updated during discovery. What is the most likely cause?
hard- A.The custom fields are not defined as 'Active' in the dictionary.
- B.The discovery probe does not have access to the custom fields.
- ✓ C.The identification rule does not include custom fields.
- D.The custom table has a stale glide record.
Why C: ServiceNow's CMDB identification and reconciliation framework uses identification rules to determine which fields are used to match CI records during discovery. Custom fields on a child table like 'u_custom_server' are not automatically included in the parent table's identification rule; they must be explicitly added to the identification rule for the CI class. Without this, the discovery probe may create duplicate CIs or fail to update those custom fields, as the system does not consider them part of the unique identifier or update set.
Variation 2. An administrator is troubleshooting why a CMDB CI's last discovered date is not updating after a successful discovery run. The CI is in a valid state and the discovery schedule runs. What could be the cause?
hard- A.The CMDB identification rule has a condition that excludes this CI from updates.
- B.The discovery source is set to 'ServiceNow' but the CI was created manually.
- ✓ C.The reconciliation rule is set to 'Manual' and the discovered data conflicts with existing data.
- D.The CI is a parent class and child class discovery is updating child records.
Why C: When a reconciliation rule is set to 'Manual', the CMDB will not automatically update CI attributes with discovered data if there is a conflict with existing data. The CI remains in its last discovered state until a manual reconciliation is performed, even if the discovery run succeeds and the CI is valid.
JA
Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
This SNOW-CSA practice question is part of Courseiva's free ServiceNow certification practice question bank. Courseiva provides original exam-style practice questions with explanations, topic-based practice, mock exams, readiness tracking, and study analytics to help learners prepare for the SNOW-CSA exam.