It's a bit hard to make sense of why some sites remain up (some with a "no new updates" banner) while others are redirected to a shutdown notice page—and in many cases it's puzzling why a shutdown would be necessary at all…..
For agencies that directly run their own Web sites on in-house servers, shutting down might make sense if the agency's "essential" and "inessential" systems are suitably segregated. Running the site in those cases eats up electricity and bandwidth that the agency is paying for, not to mention the IT and security personnel who need to monitor the site for attacks and other problems. Fair enough in those cases. But those functions are, at least in the private sector, often outsourced and paid for up front: if you've contracted with an outside firm to host your site, shutting it down for a few days or weeks may not save any money at all. And that might indeed explain why some goverment sites remain operational, even though they don't exactly seem "essential," while others have been pulled down….
Still weirder is the status of the Federal Trade Commission's site. Browse to any of their pages and you'll see, for a split second, the full content of the page you want—only to be redirected to a shutdown notice page also hosted at FTC.gov. But that means… their servers are still up and running and actually serving all the same content. In fact they're servingmore content: first the real page, then the shutdown notice page. If you're using Firefox or Chrome and don't mind browsing in HTML-cluttered text, you can even use this link to navigate to the FTC site map and navigate from page to page in source-code view without triggering the redirect. Again, it's entirely possible I'm missing something, but if the full site is actually still running, it's hard to see how a redirect after the real page is served could be avoiding any expenditures.
The determination of which services continue during an appropriations lapse is not affected by whether the costs of shutdown exceed the costs of maintaining services.
It's easy to imagine how this might often be the case: if the "inessential" public-facing Web pages are hosted on the same systems you've got to keep up and running for other "essential" back-end purposes—meaning you don't get to save the security or electricity overhead— then the cost of having IT go through and disable public access to the "inessential" sites could easily be higher than any marginal cost of actually serving the content. But the guidance here seems to require agencies to pull down "inessential" public-facing content even when this requires spending more money than leaving it up would. In the extreme case, you get the bizarre solution implemented on the FTC site: serve the content, then prevent the user from seeing it!
