Active-Directory

LDAP error 53 means the destination server is refusing a password change request. This post walks through the most common Active Directory requirements and policy settings that trigger the error.

A quick troubleshooting guide for the ‘Server not found in Kerberos database’ error, covering the four most common root causes and how to verify each one.

A practical troubleshooting guide for the Kerberos AP REP decryption error, covering the most common causes from keytab mismatches to encryption type misconfigurations.

A quick reference for diagnosing Kerberos authentication failures in Active Directory, covering the lockout state machine and the specific error codes (5be, 775, 18) that indicate revoked credentials or a locked account.

Specific JDK 1.8.0 builds (u40, u45, u91, u92) are known to break SPNEGO authentication and Hadoop web interfaces. This post documents the affected versions, the symptoms, and the recommended downgrade path.

Kerberos cross-realm authentication relies entirely on TGS exchanges between KDCs. Understanding the three-step ticket flow makes it easier to troubleshoot trust relationships between domains.