It is registered way back in 2003. may be not many popular alternatives then.

xatax · on Dec 23, 2011

StackOverflow didn't exist until 2008, so I doubt Jeff & Joel registered the name in 2003. When they bought it off whoever first registered it, they could have easily moved it to someone else. ServerFault.com (by which I mean the domain, not the site) has only existed since 2009. Clearly they had the option not to go with GoDaddy then as well, just as they did with all the other SX domains.

josephcooney · on Dec 24, 2011

really? I'm the guy that suggested the name 'stackoverflow.com' to Jeff, and at the time I suggested it it was NOT registered.

see: http://jcooney.net/post/2010/08/26/Back-in-the-day-preferred...

mr-ron · on Dec 24, 2011

Registered through: GoDaddy.com, LLC (http://www.godaddy.com) Domain Name: STACKOVERFLOW.COM Created on: 26-Dec-03 Expires on: 26-Dec-14 Last Updated on: 30-Nov-10

Though its possible that it was registered in 03, someone let it expire, and then it was up for grabs again. Im not 100% certain how the 'Created on' value works