This is generally how the GFW works in China. Instead of an overbearing nanny like a school or corporation's DNS blocker, you're left with a sense that you're on a version of the Internet that is just intermittently and somewhat mysteriously broken.

Oh boy, an excuse to share my favourite great firewall story on a visit to China. Keep in mind, this is 15 years old, so probably doesn't represent the current state of affairs. At the time, my daily news reading habit had me checking BBC and CBC (Canadian Broadcasting Corporation). The BBC site seemed to be working fine, but whenever I clicked on an article on CBC, it was blocked. A few minutes later, I went to show my wife that CBC articles were blocked, and I clicked on the same one again, and it loaded. I clicked on another: blocked. Tried it again after a few minutes and it loaded. Someone was screening the articles in real time for me. When I was done reading, I clicked on several of the weirdest headlines I could find, and after a few minutes, everything was blocked again including ones that had previously worked.