ServiceNow CMDB Interview Questions 2025
Describe the purpose of a CMDB?
A Configuration Management Database (CMDB) is a centralized repository used by organizations to store information about the components of their IT infrastructure such as IT assets, services, applications, network devices, and other critical IT components.
It is an essential part of the ITIL framework. It serves as a single source of truth, providing a unified view of all critical IT assets, their configurations, dependencies, and relationships.
it supports the processes of Change Management, Incident Management, Problem Management, Service Management, and Asset Management by linking related IT components, their configurations, and relationships.
It is an essential part of the ITIL framework. It serves as a single source of truth, providing a unified view of all critical IT assets, their configurations, dependencies, and relationships.
it supports the processes of Change Management, Incident Management, Problem Management, Service Management, and Asset Management by linking related IT components, their configurations, and relationships.
What is CI?
A specific CI refers to a single, individual instance of a configuration item that represents a particular asset, service, or component in the IT infrastructure. Each CI has a set of attributes that uniquely define it, such as its name, type, status, relationships, and other critical information relevant to the organization's IT environment.
Example: Servers, Database, Computers, Applications etc.
Example: Servers, Database, Computers, Applications etc.
What are different base tables we have in CMDB?
1. CMDB ( cmdb ) table:
This is the parent base table in ServiceNow for the Configuration Management Database (CMDB). It serves as the top-level table for all configuration items (CIs) in the CMDB.
2. Configuration Item (cmdb_ci ) table:
This is the main base table for configuration items in ServiceNow. It is the parent table from which all other more specialized CI tables extend (e.g., server, network devices, software).
3. Configuration Item Relationship ( cmdb_rel_ci ) table:
This table tracks the relationships between configuration items (CIs). It is used to define how different CIs are related to each other within the CMDB. It allows IT teams to map dependencies and relationships between CIs, which helps in change management, impact analysis, and troubleshooting.
This is the parent base table in ServiceNow for the Configuration Management Database (CMDB). It serves as the top-level table for all configuration items (CIs) in the CMDB.
2. Configuration Item (cmdb_ci ) table:
This is the main base table for configuration items in ServiceNow. It is the parent table from which all other more specialized CI tables extend (e.g., server, network devices, software).
3. Configuration Item Relationship ( cmdb_rel_ci ) table:
This table tracks the relationships between configuration items (CIs). It is used to define how different CIs are related to each other within the CMDB. It allows IT teams to map dependencies and relationships between CIs, which helps in change management, impact analysis, and troubleshooting.
What are the different types of relationships between Configuration Items?
Configuration Items can have various types of relationships that define how they interact or depend on each other. Some of the most commonly used relationships include:
1. Depends on: Indicates that one CI relies on another to function properly e.g., an application depends on a database.
2. Hosted on: Represents a relationship where a CI is hosted on another CI, such as an application being hosted on a server.
3. Connects to: Shows that two CIs are connected, typically for data transfer or communication purposes e.g., a router connects to a switch.
4. Runs on: Describes a CI that operates on top of another CI, often used for software running on hardware e.g., a service runs on a server.
Note: There are many more relationship types that define the connections between CIs. These are stored in the cmdb_rel_type table in ServiceNow. For a complete list and further details on all available relationship types, you can refer to the cmdb_rel_type table.
1. Depends on: Indicates that one CI relies on another to function properly e.g., an application depends on a database.
2. Hosted on: Represents a relationship where a CI is hosted on another CI, such as an application being hosted on a server.
3. Connects to: Shows that two CIs are connected, typically for data transfer or communication purposes e.g., a router connects to a switch.
4. Runs on: Describes a CI that operates on top of another CI, often used for software running on hardware e.g., a service runs on a server.
Note: There are many more relationship types that define the connections between CIs. These are stored in the cmdb_rel_type table in ServiceNow. For a complete list and further details on all available relationship types, you can refer to the cmdb_rel_type table.
What is IRE in CMDB?
The Identification and Reconciliation Engine (IRE) in ServiceNow is a critical part of the Configuration Management Database (CMDB) process that helps maintain an accurate and consistent CMDB.
It ensures that Configuration Items (CIs) discovered by tools such as ServiceNow Discovery or manually entered data are correctly identified, matched, and reconciled against existing data in the CMDB.
It is responsible for identifying CIs, resolving discrepancies in the data, and ensuring that there are no duplicates in the CMDB. It helps maintain data accuracy by automatically matching and reconciling new, updated, or conflicting CI records based on predefined rules.
It ensures that Configuration Items (CIs) discovered by tools such as ServiceNow Discovery or manually entered data are correctly identified, matched, and reconciled against existing data in the CMDB.
It is responsible for identifying CIs, resolving discrepancies in the data, and ensuring that there are no duplicates in the CMDB. It helps maintain data accuracy by automatically matching and reconciling new, updated, or conflicting CI records based on predefined rules.
What is the purpose of Identification rules?
It works by identifying CIs based on the incoming discovery data (like IP address, hostname, serial number, MAC address, etc.). When ServiceNow Discovery or any other integration tool finds a CI, the Identification Engine tries to match the new data to the existing records in the CMDB.
The goal is to either:
- Match the discovered data with an existing CI in the CMDB, or
- Create a new CI if no match is found.
The goal is to either:
- Match the discovered data with an existing CI in the CMDB, or
- Create a new CI if no match is found.
What is the purpose of Reconciliation rules?
Reconciliation rules ensure the consistency and accuracy of the CMDB by handling discrepancies between newly discovered data and existing records. They resolve conflicts, such as duplicate or conflicting data (e.g., IP addresses, hostnames), by applying predefined rules to determine how to merge or update the data from different sources. This helps maintain an accurate and reliable CMDB.
What is dependency view map in CMDB?
A Dependency View Map is a visual representation that shows the relationships between different Configuration Items (CIs) within an organization’s IT infrastructure.
This map helps IT teams understand how various components of the infrastructure depend on each other and interact.
Dependency View Sample Map:
This map helps IT teams understand how various components of the infrastructure depend on each other and interact.
What is difference between Asset and CI?
An Asset refers to physical or non-physical items owned or leased by an organization that have financial value, while a Configuration Item (CI) is any component or service within the IT infrastructure that needs to be managed for IT service delivery.
Some items can be both an Asset and a CI, as they require both operational support and financial tracking. Asset management focuses on the financial lifecycle of an item, whereas CI management focuses on the operational and service-related aspects.
Some items can be both an Asset and a CI, as they require both operational support and financial tracking. Asset management focuses on the financial lifecycle of an item, whereas CI management focuses on the operational and service-related aspects.
Name 5 important CMDB child tables with their overview.
1. Computer (cmdb_ci_computer): This table stores information about both physical and virtual computers, including servers, workstations, and other computing devices in the organization’s infrastructure.
2. Network (cmdb_ci_network): This table contains details about network-related devices such as routers, switches, firewalls, and other components that support the organization’s network infrastructure.
3. Storage Device (cmdb_ci_storage): This table tracks information about storage systems, including storage area networks (SAN), network-attached storage (NAS), and other types of storage devices used within the organization.
4. Database (cmdb_ci_database): This table holds information about databases (e.g., Oracle, SQL Server, MySQL) that support applications or infrastructure systems, ensuring proper tracking of database components.
5. Application (cmdb_ci_application): This table records details about software applications and services that are part of the organization's infrastructure, including both enterprise applications and custom software solutions.
2. Network (cmdb_ci_network): This table contains details about network-related devices such as routers, switches, firewalls, and other components that support the organization’s network infrastructure.
3. Storage Device (cmdb_ci_storage): This table tracks information about storage systems, including storage area networks (SAN), network-attached storage (NAS), and other types of storage devices used within the organization.
4. Database (cmdb_ci_database): This table holds information about databases (e.g., Oracle, SQL Server, MySQL) that support applications or infrastructure systems, ensuring proper tracking of database components.
5. Application (cmdb_ci_application): This table records details about software applications and services that are part of the organization's infrastructure, including both enterprise applications and custom software solutions.
What are 3C's in CMDB?
The 3Cs—Completeness, Correctness, and Compliance—are key principles that ensure the quality and reliability of data within the CMDB. These principles help maintain high-quality configuration data and improve decision-making and operational processes across the organization.
1. Completeness: It refers to ensuring that the CMDB contains all the necessary Configuration Items (CIs) and attributes that represent the full scope of the IT environment.
2. Correctness: It refers to the accuracy of the data stored in the CMDB. It ensures that the details and attributes of each Configuration Item (CI), including relationships and dependencies, are correctly represented.
3. Compliance: It refers to ensuring that the data in the CMDB adheres to organizational standards, policies, regulatory requirements and best practices. This includes maintaining consistency in naming conventions, CI categorization, data formats, and ensuring that proper controls and audits are in place.
1. Completeness: It refers to ensuring that the CMDB contains all the necessary Configuration Items (CIs) and attributes that represent the full scope of the IT environment.
2. Correctness: It refers to the accuracy of the data stored in the CMDB. It ensures that the details and attributes of each Configuration Item (CI), including relationships and dependencies, are correctly represented.
3. Compliance: It refers to ensuring that the data in the CMDB adheres to organizational standards, policies, regulatory requirements and best practices. This includes maintaining consistency in naming conventions, CI categorization, data formats, and ensuring that proper controls and audits are in place.
What is CMDB Health Dashboard?
CMDB Health Dashboard is a tool that provides a visual representation of the health and quality of the dataThe primary use of the CMDB Health Dashboard in ServiceNow is to monitor and assess the overall health and quality of the data within the Configuration Management Database (CMDB).
It provides a visual overview of key metrics related to data completeness, accuracy, and consistency, helping organizations ensure that the CMDB remains reliable and up-to-date.
Key purposes of the CMDB Health Dashboard:
Identify Data Issues: It highlights discrepancies such as missing, incomplete, or incorrect data, including issues like missing relationships between Configuration Items (CIs).
Track Data Quality: Provides visibility into the health of the CMDB, allowing users to track data quality trends over time.
Reconciliation Monitoring: Displays results of reconciliation processes, helping to spot and resolve conflicts between discovered data and existing records.
Actionable Insights: Helps prioritize areas for improvement by presenting key indicators that affect data quality, enabling users to take corrective actions.
It provides a visual overview of key metrics related to data completeness, accuracy, and consistency, helping organizations ensure that the CMDB remains reliable and up-to-date.
Key purposes of the CMDB Health Dashboard:
Identify Data Issues: It highlights discrepancies such as missing, incomplete, or incorrect data, including issues like missing relationships between Configuration Items (CIs).
Track Data Quality: Provides visibility into the health of the CMDB, allowing users to track data quality trends over time.
Reconciliation Monitoring: Displays results of reconciliation processes, helping to spot and resolve conflicts between discovered data and existing records.
Actionable Insights: Helps prioritize areas for improvement by presenting key indicators that affect data quality, enabling users to take corrective actions.
What is a Data Certification Process in ServiceNow CMDB?
The Data Certification Process in ServiceNow CMDB is designed to validate, review, and certify the accuracy of the CMDB data by assigning responsibility to specific users or groups.
It ensures that the information about Configuration Items is reliable, up-to-date, and compliant with organizational standards, thereby improving data quality and supporting better IT service management.
It ensures that the information about Configuration Items is reliable, up-to-date, and compliant with organizational standards, thereby improving data quality and supporting better IT service management.
What is Service Mapping, and how is it related to CMDB?
Service mapping is used to discover and track IT applications and components in an organization, outlining how each connects to business services.
The primary goal of Service Mapping is to provide visibility into how business services are delivered and supported by the IT infrastructure.
The primary goal of Service Mapping is to provide visibility into how business services are delivered and supported by the IT infrastructure.
How Asset- CI creation works in ServiceNow?
In ServiceNow, the process of creating a CI and linking it to an Asset involves several steps to ensure accurate tracking of both technical and financial data.
1. CI Creation: When a new CI is created (e.g., a computer or server), the model of the CI must be specified. This model is typically referenced from the cmdb_model table, which contains predefined models for various assets.
2. Asset Model Verification: ServiceNow verifies whether the specified CI model exists and is properly configured in the cmdb_model table. If no model is selected or if the model is not available or incorrectly configured, the system will not create an asset for the CI.
3. Asset Creation: If the model is found and properly configured, ServiceNow automatically creates an Asset record in the alm_asset table. This asset record will inherit relevant information such as:
Model
Serial number
Purchase cost
4. Linking the CI and Asset: Once the Asset is created, it is linked to the CI through the Asset field in the CI record. This establishes a relationship between the technical configuration details (CI) and the financial tracking information (Asset).
Technical details for reference: A Business Rule called "Create Asset from CI" is responsible for automating the creation of the Asset record whenever a new CI is created and meets the necessary criteria.
1. CI Creation: When a new CI is created (e.g., a computer or server), the model of the CI must be specified. This model is typically referenced from the cmdb_model table, which contains predefined models for various assets.
2. Asset Model Verification: ServiceNow verifies whether the specified CI model exists and is properly configured in the cmdb_model table. If no model is selected or if the model is not available or incorrectly configured, the system will not create an asset for the CI.
3. Asset Creation: If the model is found and properly configured, ServiceNow automatically creates an Asset record in the alm_asset table. This asset record will inherit relevant information such as:
Model
Serial number
Purchase cost
4. Linking the CI and Asset: Once the Asset is created, it is linked to the CI through the Asset field in the CI record. This establishes a relationship between the technical configuration details (CI) and the financial tracking information (Asset).
Technical details for reference: A Business Rule called "Create Asset from CI" is responsible for automating the creation of the Asset record whenever a new CI is created and meets the necessary criteria.
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User Added Interview Question and Answers
Shivam 2025-09-23 05:28:01
What will be empact if delete in ci record
0 Helpfuls
Yasar 2025-05-13 15:36:30
How to check Duplicate CIs in CMDB and fix duplicate CIs issue
0 Helpfuls
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