Some Mac users have discovered that the hosts file in MacOS does not appear to work, or changes to the /etc/hosts file on the Mac are seemingly ignored. Given that the hosts file is used to map IP addresses to host names, and is frequently modified by advanced users, this is an understandably annoying problem.
This is fairly obvious issue when it happens, because after editing the hosts file on a Mac from the command line or even with TextEdit, and flushing DNS cache, there does not appear to be any change to hosts.
Changes to the hosts file being ignored, or edits to the hosts file not working, are actually a fairly common occurrence, particularly with modern versions of MacOS system software. Fortunately it’s also usually a really easy fix.