The Kerberos authentication protocol includes some countermeasures. In the classic case of a replay attack, a message is captured by an adversary and then replayed at a later date in order to produce an effect. For example, if a banking scheme were to be vulnerable to this attack, a message which results in the transfer of funds could be replayed over and over to transfer more funds than originally intended. However, the Kerberos protocol, as implemented in Microsoft Windows Active Directory, includes the use of a scheme involving time stamps to severely limit the effectiveness of replay attacks. Messages which are past the "time to live (TTL)" are considered old and are discarded.[5]