Top CMDB & Discovery Interview Questions

[SD_Chandan]

• CMDB (Configuration Management Database)
  
   What is the purpose of the CMDB in ServiceNow?
   How do you define a Configuration Item (CI) in ServiceNow?
   What are CI relationships and how are they used in impact analysis?
   How do you maintain data integrity in the CMDB?
   What is the difference between a CI and an asset?
   How do you use CI classes and class hierarchy in CMDB?
   What are identification and reconciliation rules in CMDB?
   How do you manage CI lifecycle in ServiceNow?
   What tools or integrations can populate the CMDB automatically?
   How do you troubleshoot discrepancies in CMDB data?
  
  
• Discovery
  
  What is ServiceNow Discovery and what problem does it solve?
  What is the role of a MID Server in Discovery?
  How do probes and sensors work in the Discovery process?
  What are patterns in Discovery and how are they used?
  How do you configure credentials for Discovery?
  What are the steps involved in a horizontal Discovery?
  How do you troubleshoot a failed Discovery?
  What is the difference between horizontal and vertical Discovery?
  How does Discovery integrate with the CMDB?
  What are best practices for scheduling Discovery scans?

[SD_Chandan · Accepted solution]

Sample Answers 

1. What is the purpose of the CMDB in ServiceNow?
   The CMDB stores information about Configuration Items (CIs) and their relationships. It helps in impact analysis, change planning, and incident resolution by providing a centralized view of IT infrastructure.
2. How do you define a Configuration Item (CI) in ServiceNow?
   A CI is any component that needs to be managed to deliver a service, such as servers, applications, or network devices. CIs are stored in the cmdb_ci table and its child tables.
3. What are CI relationships and how are they used in impact analysis?
   CI relationships define how CIs are connected (e.g., depends on, runs on). They are used in impact analysis to understand the effect of changes or outages on related services.
4. How do you maintain data integrity in the CMDB?
   By using identification and reconciliation rules, data certification, CMDB Health Dashboard, and automated discovery tools to ensure accuracy and completeness.
5. What is the difference between a CI and an asset?
   A CI represents a logical or physical component in the CMDB, while an asset is a financial or inventory record. A CI can be linked to an asset, but they serve different purposes.
6. How do you use CI classes and class hierarchy in CMDB?
   CI classes define the type of CI (e.g., Server, Database). The class hierarchy allows inheritance of attributes and helps organize CIs logically.
7. What are identification and reconciliation rules in CMDB?
   Identification rules determine if a discovered record matches an existing CI. Reconciliation rules decide which data source is authoritative when multiple sources provide data.
8. How do you manage CI lifecycle in ServiceNow?
   By tracking CI states (e.g., Installed, In Maintenance, Retired) and automating transitions using workflows or Discovery updates.
9. What tools or integrations can populate the CMDB automatically?
   ServiceNow Discovery, Service Mapping, third-party integrations (e.g., SCCM, AWS), and manual imports using Transform Maps.
10. How do you troubleshoot discrepancies in CMDB data?
    Using the CMDB Health Dashboard, audit logs, reconciliation logs, and reviewing Discovery logs to identify and correct inconsistencies.
11. What is ServiceNow Discovery and what problem does it solve?
    Discovery identifies devices and applications on your network and populates the CMDB with accurate, up-to-date data, reducing manual entry and errors.
12. What is the role of a MID Server in Discovery?
    The MID Server acts as a secure communication bridge between ServiceNow and the target infrastructure, executing probes and collecting data.
13. How do probes and sensors work in the Discovery process?
    Probes gather raw data from target systems. Sensors process that data and populate the CMDB with structured CI records.
14. What are patterns in Discovery and how are they used?
    Patterns are reusable logic used to discover complex applications and services. They define steps to identify, classify, and populate CI data.
15. How do you configure credentials for Discovery?
    Credentials are stored securely in the Credentials table and associated with Discovery schedules or IP ranges. They are selected automatically based on matching rules.
16. What are the steps involved in a horizontal Discovery?
    Horizontal Discovery includes scanning IP ranges, identifying devices, classifying them, and populating the CMDB with infrastructure CIs.
17. How do you troubleshoot a failed Discovery?
    By reviewing Discovery logs, MID Server logs, checking credentials, firewall rules, and ensuring the target is reachable.
18. What is the difference between horizontal and vertical Discovery?
    Horizontal Discovery finds infrastructure components (e.g., servers), while vertical Discovery maps applications and their dependencies.
19. How does Discovery integrate with the CMDB?
    Discovery updates or creates CIs in the CMDB using identification and reconciliation rules, ensuring accurate and non-duplicated data.
20. What are best practices for scheduling Discovery scans?
    Schedule during off-peak hours, segment by IP ranges, use credential affinity, and monitor performance to avoid network overload.