Comment by 3xblah

In the article there is an example of a blog post that is missing on blog.facebook.com but can be found on web.archive.org. I could be wrong but I think changes to robots.txt can make pages "disappear" from Internet Archive, too. Many have made the mistake of assuming what is at web.archive.org is "permanent" only to watch it "disappear" when the domain name registration lapses and robots.txt changes.