Failed Login?

Failed Login?

Hi everyone,

I'm seeing this error message flooding our domain controllers under the security logs about 2-3 seconds.

Pre-authentication failed:
     User Name:    Helpdesk
     User ID:        Domain1\Helpdesk
     Service Name:    krbtgt/Domain1.COM
     Pre-Authentication Type:    0x0
     Failure Code:    0x19
     Client Address:    10.121.1.12

10.121.1.12 is our helpdesk server. We're using Active Directory authentication (NOT pass through) for technicians and requesters and that's working. The email fetching is working fine too so I can't think of what would be causing these errors. Any thoughts?