New
#31
How about this wild guess. There's a large number of servers. They aren't all on the same IP address. The update program on your computer has been assigned an IP to go to and the date you are eligible downloaded in one of the many previous updates. The IP is based on your OS, if and when (!) you signed up for Win 10 and your product key. That would be a moderately simple process compared to designing the whole new OS.
Alternately its a free-for-all and the biggest DOS attack you've ever seen.