The KDC encountered duplicate names while processing a Kerberos authentication request

Hi guys,

I wonder if anyone there could show me the way to get out from this,

I've got plenty of messages in System event viewer about:

case1:

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The KDC encountered duplicate names while processing a Kerberos authentication request. The duplicate name is MSSQLSvc/CSOPTO-FS1.csopto.com:bkupexec (of type DS_SERVICE_PRINCIPAL_NAME). This may result in authentication failures or downgrades to NTLM. In order to prevent this from occuring remove the duplicate entries for MSSQLSvc/CSOPTO-FS1.csopto.com:bkupexec in Active Directory.

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tHANKS

- <Event xmlns="http://schemas.microsoft.com/win/2004/08/events/event">

- <System>

  <Provider Name="Microsoft-Windows-Kerberos-Key-Distribution-Center" Guid="{3FD9DA1A-5A54-46C5-9A26-9BD7C0685056}" EventSourceName="KDC" />

  <EventID Qualifiers="49152">11</EventID>

  <Version>0</Version>

  <Level>2</Level>

  <Task>0</Task>

  <Opcode>0</Opcode>

  <Keywords>0x80000000000000</Keywords>

  <TimeCreated SystemTime="2015-05-21T02:03:05.000Z" />

  <EventRecordID>288348</EventRecordID>

  <Correlation />

  <Execution ProcessID="0" ThreadID="0" />

  <Channel>System</Channel>

  <Computer>CSOPTO-FS1.csopto.com</Computer>

  <Security />

  </System>

- <EventData>

  <Data Name="Name">MSSQLSvc/CSOPTO-FS1.csopto.com:bkupexec</Data>

  <Data Name="Type">DS_SERVICE_PRINCIPAL_NAME</Data>

  <Binary />

  </EventData>

  </Event>

********************************************

case2:

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A Kerberos Error Message was received:

 on logon session

 Client Time:

 Server Time: 2:3:5.0000 5/21/2015 Z

 Error Code: 0x7  KDC_ERR_S_PRINCIPAL_UNKNOWN

 Extended Error: 0xc0000035 KLIN(0)

 Client Realm:

 Client Name:

 Server Realm: CSOPTO.COM

 Server Name: MSSQLSvc/CSOPTO-FS1.csopto.com:bkupexec

 Target Name: MSSQLSvc/CSOPTO-FS1.csopto.com:bkupexec@CSOPTO.COM

 Error Text:

 File: 9

 Line: e2d

 Error Data is in record data.

 

*********************************

 

- <Event xmlns="http://schemas.microsoft.com/win/2004/08/events/event">

- <System>

  <Provider Name="Microsoft-Windows-Security-Kerberos" Guid="{98E6CFCB-EE0A-41E0-A57B-622D4E1B30B1}" EventSourceName="Kerberos" />

  <EventID Qualifiers="32768">3</EventID>

  <Version>0</Version>

  <Level>2</Level>

  <Task>0</Task>

  <Opcode>0</Opcode>

  <Keywords>0x80000000000000</Keywords>

  <TimeCreated SystemTime="2015-05-21T02:03:05.000Z" />

  <EventRecordID>288349</EventRecordID>

  <Correlation />

  <Execution ProcessID="0" ThreadID="0" />

  <Channel>System</Channel>

  <Computer>CSOPTO-FS1.csopto.com</Computer>

  <Security />

  </System>

- <EventData>

  <Data Name="LogonSession" />

  <Data Name="ClientTime" />

  <Data Name="ServerTime">2:3:5.0000 5/21/2015 Z</Data>

  <Data Name="ErrorCode">0x7</Data>

  <Data Name="ErrorMessage">KDC_ERR_S_PRINCIPAL_UNKNOWN</Data>

  <Data Name="ExtendedError">0xc0000035 KLIN(0)</Data>

  <Data Name="ClientRealm" />

  <Data Name="ClientName" />

  <Data Name="ServerRealm">CSOPTO.COM</Data>

  <Data Name="ServerName">MSSQLSvc/CSOPTO-FS1.csopto.com:bkupexec</Data>

  <Data Name="TargetName">MSSQLSvc/CSOPTO-FS1.csopto.com:bkupexec@CSOPTO.COM</Data>

  <Data Name="ErrorText" />

  <Data Name="File">9</Data>

  <Data Name="Line">e2d</Data>

  <Binary>3015A103020103A20E040C350000C00000000001000000</Binary>

  </EventData>

  </Event>

 

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May 20th, 2015 10:47pm

Hi, Please go through the below link for similar issue and follow MS article. https://social.technet.microsoft.com/Forums/forefront/en-US/ffdafd68-9645-4281-86f7-d54d289037d9/kdc-encountered-duplicate-names-while-processing-a-kerberos-authentication-request?forum=winserverDS
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May 21st, 2015 12:23am

Mine a bit different from it, it related the duplicate SPN with backupexec 2014 software.. i try to digest the article as much as i can...
May 21st, 2015 12:55am

Have you try and search the object in AD . it must be in multiple OU with same entry or different OU.

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May 21st, 2015 12:58am