12 April,16 at 11:02 AM
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Cause:
This may happen in AD environments where an authoritative restore of krbtgt was done. This causes the kpasswd protocol to
fail with KDC_ERR_S_PRINCIPAL_UNKNOWN error which prevents join of Unix or Mac machines to the domain.
Resolution:
This is a Microsoft defect and a hotfix was issued. Please download and apply the hotfix as stated in http://support.microsoft.com/kb/976424