ORA-12631 / TNS-12631: Username retrieval failed

From Metalink:
Problem Description:
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If you want to check the TNS-12631 error, check “sqlnet”. “You will find a TNS-12631 error.
ora-12570/TNS-12570: TNS:Package Reader Failure
ora – 12631/TNS – 12631: username retrieval failed

Problem Statement:
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These errors are related to remote authentication in NT NT (NT Transport Services).
In fact, the following parameter is set in “SQLNET. ora”:
As a result, if you are logged in as a domain user and you do not have a network connection (network cable temporarily removed or laptop booted independently), you will not be able to connect to the database because authentication will attempt to reach the domain user database (primary domain controller) or BDC (backup domain controller) on the PDC.

Solution Description:
===================== ====== You can log in as an NT local user. You can disable NTS in sqlnet. by setting the following parameters:

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1. when you log in as a local user, you will be exposed to the local user database, not the remote domain user database. When NTS is disabled, you will not access the domain user database even if you are logged in as a domain user.

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