Based on an analysis of the process, the AD server will always record an event for pre-authentication required while it is a normal process. You can safely ignore this security event.
However, if you want to disable logging of the pre-authentication events for the admin account that IWSVA uses:
- In AD, go to the property of the admin account.
- Click the Account tab.
- Under Account options section, tick the Do not require Kerberos pre-authentication check box.
