For how many days we can get the audit.log - in splunk ?

Since 5th December 2012 , I am using Splunk on windows OS. For audit purpose i need the audit.log files from December 2012 to Till date . But, I could found audit.log files available only for this June month only. Whether the old audit.log will be archived somewhere? or deleted ? Where can i get the configurations for log files ?

Kindly please help me in this.