Date Display Format
The format in which various domain name management software tools display the dates is set using the Windows Control Panel. Don’t confuse this with the date format in the “Whois Configuration” dialog.
It is always safer to set a display format that shows the month as name and not as a number. Otherwise there is always a possibility confusion between dates and months. Please see the screen shot below.

Date Extraction Format for Whois
The data format in “whois setup” specifies the format used by the registry and registrar to specify the dates. This is required so that the software can extract the dates properly.