If you've tried to reach a government site today, you may have noticed that the "shutdown" applies to the virtual homes and social media accounts of federal agencies no less than their brick-and-mortar offices... at least some them. 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. With the offices closed, you might not have personnel on hand to add new content or other updates, but is pulling the existing content down strictly necessary?
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.
That doesn't seem to account for some of the weird patterns we see, however. The main page at NASA.gov redirects to a page saying the site is unavailable, but lots of subdomains that, however cool, seem "inessential" remain up and running: the "Solar System Exploration" page at solarsystem.nasa.gov; the Climate Kids website at climatekids.nasa.gov; and the large photo archive at images.jsc.nasa.gov, to name a few. There are any number of good reasons some of those subdomains might be hosted separately, and therefore unaffected by the shutdown—but it seems odd they can keep all of these running without additional expenditures, yet aren't able to redirect to a co-located mirror of the landing page.
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 serving more 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.
One possible answer can be found in the policy governing shuttering of government Web sites—which, as blogger Jon Christian noted, stipulates that:
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!
I don't know enough about the rules of government shutdowns to say whether this strange result is a bit of Washington Monument Syndrome in action or a perverse but unavoidable consequence of the Antideficiency Act, but either way it seems like an awfully strange approach.