Understanding 0.0.0.0 in /etc/hosts
I'm a little confused about the meaning of the address 0.0.0.0 in Lab 35.2. Looking at the list of addresses in hosts.txt I get the impression that adding these to /etc/hosts should block them. But it doesn't. Taking adgrx.com as an example, I can ping it and its IP address is 220.127.116.11 and I can view it in a browser. After appending hosts.txt to /etc/hosts it pings at 127.0.0.1. But it still comes up in the browser, even after I clear the cache and do a hard reload. The ping at 127.0.0.1 I kind of get, but not completely. But I would expect to get a "page not found" in the browser. Can somebody explain this to me? Thanks. I'm using Firefox in a virtual Ubuntu 18.04.