Hi @ShashikantP7021 ,

Please find the answers below

1.if there are 1000 ci updating only 600 how you will identify that ci ?
[GK] : You can check the 'Most recent discovery' & 'Discovery source' field in CMDB table

2.how discovery works ?
[GK]: There are four phases in discovery
Scanning, Classification, Identification and exploration
Scan - Trigger probes like "Shazzam" to identify IP addresses and determine which ports are open
Classify - Classify the discovered devices based on operating system and device type
Identify - Check the CMDB for existing records of the discovered device
Explore - Gather additional information about by triggering additional probes

https://www.servicenow.com/community/itom-articles/understand-phases-of-discovery/ta-p/3116984

3.how you will maintain the cmdb ?
[GK]: There are multiple CMDB management tools like CMDB Data Manager, CMDB Workspace, Query Builder, CMDB & CSDM dashboard and CI class manager are available in ServiceNow to manage CMDB

4.how you will find out the duplicate ?

[GK]: You can check the 'Duplicate of' field in CMDB table or de-duplication task in CMDB workspace

BR,

Gomathi K