How to trace and diagnose account lockout in AD?
An account gets locked out if the bad password count exceeds the threshold limit. If account lockouts are not identified and fixed immediately, they could cause a great deal of problems. Use the following steps to identify locked out accounts:
Step 1 - Search the domain controller possessing the PDC Emulator Role
<get-addomain→.pdcemulator <domain name→
Step 2- Search for Event ID 4740
Go to the event log viewer of the DC holding PDC emulator role and in its security logs, search for Event ID 4740.
Step 3 - Apply appropriate filters
You can apply filters in case you want a more customized report such as looking for lockouts that happened during the last one hour, to find the recent lockout source of a particular user.
Step 4 - Find the locked out user event report from the log
Click Find from the actions pane to search for the User whose account is locked out.
Step 5 - Open the event report to track the source of the locked out account
Here you can find the name of the user account and the source of the lockout location as well in the ‘Caller Computer Name’ column.