Every 60 minutes Windows copies the DHCP settings to the %systemroot%\system32\dhcp\Backup\new directory. And these copies can be easily secured by any backup software since the files are not open. You can change this time interval in the Registry:

KEY_LOCAL_MACHINE\System\CurrentControlSet\services\DHCPServer\Parameters

The minimum setting of “Backupinterval” is 5 minutes, the maximum 60 minutes.