WebSite Machine Registration

I apologize if I'm posting this in the wrong group but since I don't
know the answer to my question, I have no idea where it should be
posted. I have seen several banking websites that are able to
determine that I'm connecting from different machines. The websites
register each one asking extra security questions before allowing the
new machine to be used with the website. I have deleted all temporary
internet files and all cookies as a test and the website still knows
my machine has been previously registered. So information stored in
cookies is not the answer. Does anyone know how this is done?
.