This book support site was hosted by a simple account's web pages since the mid-1990s (1995 or 1996, as far as I can reconstruct). It began its life on a server and domain name run by rmi.net (Rocky Mountain Internet, an early dial-up provider); which was later acquired by Mindspring; which was eventually bought by Earthlink. Along the way, the original www.rmi.net/~lutz URL kept working reasonably well, so there was little incentive to change the domain name or host for a non-commercial resources site whose location was published in some half million books.
And then the reality of today's web struck. On October 24, 2015, the address of one of this site's pages was posted on a high-volume forum (Hacker News is a prime suspect), attracting over 10,000 visitors to the page in a day and a half. Traffic is a great problem to have, but this caused the site to exceed its archaic bandwidth quota and be shut down completely for an entire week, denying access to an untold number of readers. Earthlink proved characteristically inflexible on the issue (they've also changed URL structure and other service components in the past, with neither notice nor recourse).
Consequently, after two decades, the site has finally been moved to a Godaddy web hosting account and server as of October 26, 2015, using a custom registered domain name for its new URL: learning-python.com. The new URL should prove more stable, and the new unlimited-bandwidth host will accommodate both higher traffic rates, and new functionality in the future, including Python-coded server-side interaction scripts. The prior site's location will maintain redirection pages until its traffic fades.
I regret any confusion the move may cause, and the books site resisted a commercially based presence as long as it could; but working at a different URL beats not working at all. The new scheme will hopefully weather the years as well as the former—though the Internet seems likely to be as different two decades hence as it was two decades ago. All of which might embed a lesson for prudent readers about becoming overly dependent on web-based companies in general. Today's cloud providers and social media sites, for example, could very well be tomorrow's multiply acquired ghost companies.