A statement that includes the AS DEFAULT option has no effect on the logon access granted to or revoked from specific user names. A user named in a GRANT LOGON statement can always access the applicable client system even if that client has a default of REVOKE, and a user named in a REVOKE LOGON statement cannot access the applicable client system even if that client has a default of GRANT.
For a GRANT LOGON statement, the system checks that the requesting user has EXECUTE privilege on the associated system macro. However, the system does not check whether the user names the statement defines apply to users owned by the requesting user. If the system cannot verify the statement because, for example, it specifies a nonvalid user name or an invalid host ID, the system takes no action.