Principal classes in CMDB success advisor

  • Release version: Zurich
  • Updated February 24, 2026
  • 3 minutes to read
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    Summary of Principal classes in CMDB success advisor

    Principal classes are Configuration Item (CI) classes that your organization identifies as important within ServiceNow's CMDB success advisor. These classes define the scope of the Data Foundations advisor, which automatically marks them as principal on your instance. This designation applies an automatic filter to the Configuration Item field on task records, focusing CMDB data quality efforts on the most relevant classes for your business.

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    Key Features

    • Automatic Marking: When you select CI classes during Data Foundations scope setup, they are automatically marked as principal.
    • Relevance-Based Recommendations: CMDB success advisor analyzes the last 180 days of incident, problem, and change activity to rank CI classes by relevance, helping you choose the right principal classes.
    • Continuous Monitoring: Data quality of principal classes is continuously tracked via the Data Foundations advisor dashboard.
    • Customizable System Properties: Administrators with sncmdbadmin role can adjust properties controlling recommendation periods, number of recommended classes, inclusion of custom CI classes, and fallback recommendations for instances without task history.
    • Manual Synchronization: Principal class designations made outside CMDB success advisor are not automatically reflected in the Data Foundations advisor scope, requiring manual updates to keep scopes in sync.

    Practical Application for ServiceNow Customers

    By designating principal classes thoughtfully, you ensure your CMDB remains focused on the CI classes that matter most, improving the accuracy and effectiveness of data quality efforts. Use the CMDB success advisor’s guided recommendations to select principal classes based on your organization's recent operational activity. Manage principal classes directly within CMDB success advisor to maintain synchronization and avoid discrepancies in the Data Foundations advisor scope. Leverage system properties to tailor the advisor’s recommendations to your instance’s specific needs, especially if your environment has unique or custom CI classes.

    Key Outcomes

    • Maintained focus on high-value CI classes improves overall CMDB data quality.
    • Streamlined principal class management via automated recommendations and continuous monitoring.
    • Clear guidance and controls help align CMDB success advisor scope with organizational priorities.
    • Reduced risk of data inconsistencies by managing principal class updates within the CMDB success advisor interface.

    Principal classes are CI classes that your organization designates as important. In CMDB success advisor, the CI classes you select define the Data Foundations advisor scope, and CMDB success advisor automatically marks them as principal on your instance.

    A principal CI class is a CI class that your organization has designated as important. When you set up your Data Foundations scope, the CI classes you select are automatically marked as principal on your ServiceNow instance.

    After a CI class is designated as principal, an automatic filter is applied to the Configuration Item field on task records.

    Principal classes benefits

    Selecting the right principal classes keeps your CMDB focused and accurate. The CMDB success advisor measures and improves data quality for the classes that matter most to your business.

    Principal class selection

    CMDB success advisor processes your instance's history and ranks CI classes by relevance before you set up your advisor scope.

    For guidance on choosing the right classes, see the Guidance on designating principal classes in the CMDB [KB2707240] article in the Now Support Knowledge Base.

    You can manage the most important CI classes with CMDB success advisor by:

    • Selecting CI classes from the grouped, recommended list in the Data Foundations scope setup. Classes are marked as principal automatically when you save.
    • Using intelligent recommendations based on the past 180 days of incident, problem, and change activity on your instance.
    • Monitoring data quality continuously through the Data Foundations advisor dashboard.

    Principal class tracking in CMDB success advisor

    Use the following system properties to customize how CMDB success advisor recommends and manages principal classes. Users with the sn_cmdb_admin role can adjust these properties to control the scope and quality of principal class recommendations.

    Table 1. System properties in CMDB success advisor for principal classes
    Property Purpose
    sn_cmdb_advisor.principal_class_suggestion_period Number of days of task history CMDB success advisor scans when generating class recommendations.

    Default value: 180 days
    sn_cmdb_advisor.suggested_principal_classes_limit Maximum number of recommendations shown in the Recommended group.

    Default value: 20
    sn_cmdb_advisor.principal_class_others Comma-separated list of custom CI classes to include in the Others group of the Manage principal classes selection.
    Note:
    Use this property when the custom CI classes aren't available in the predefined Data Foundations advisor scope setup list.
    sn_cmdb_advisor.principal_class_recommendation_criteria Keyword value (PREDEFINED) that causes CMDB success advisor to recommend a standard set of commonly managed CI classes on instances with no prior task activity. This property does not exist by default and must be created manually.

    The sn_cmdb_advisor.principal_class_recommendation_criteria property is optional. Create it on instances with no prior task activity, where task-based recommendations produce no results. Setting the value to PREDEFINED causes CMDB success advisor to recommend a standard set of commonly managed CI classes. For instructions, see Create the principal class recommendation criteria property.

    Principal class synchronization

    The Data Foundations advisor stores its own record of which CI classes are in scope. The advisor does not automatically reflect changes to principal class designations made through CI Class Manager or directly on the instance. A comparison runs when you open the dashboard to identify any discrepancies.

    Consider the following behavior:

    • When you mark a class as principal outside CMDB success advisor, the class is marked as principal on the instance. This applies after the Data Foundations advisor dashboard scope is configured. However, it isn't automatically added to the Data Foundations advisor dashboard scope.
    • When you remove the principal designation from a class outside the advisor, the class remains in the Data Foundations advisor dashboard scope until you remove it manually.

    To keep the Data Foundations advisor dashboard scope accurate, make all principal class updates directly in CMDB success advisor by selecting Manage principal classes on the Data Foundations advisor dashboard. For more information, see Manage Data Foundations advisor scope in CMDB success advisor.

    If other tools or processes change principal classes outside the advisor, an out-of-sync notification appears when you open the Data Foundations advisor dashboard. For more information, see Principal class sync in Data Foundations advisor.