Firefox only sees the first entry defined in /etc/hosts for 127.0.0.1. Basically, Firefox is not seeing the modifications to the DNS entries I've made in /etc/hosts. Chrome is. However, later I noticed that Safari is not seeing them as well. After the troubleshooting below, I fixed the problem by moving all my /etc/hosts declarations to different lines as per here: http://www.justincarmony.com/blog/2011/07/27/mac-os-x-lion-etc-hosts-bugs-and-dns-resolution/ I have no idea why that works. But it does fix the issue for Firefox and Safari. I tried a couple of things as per this thread: https://support.mozilla.org/en-US/questions/1011327 Things I tried (typing about:config into address bar): set keyword.enabled to false set browser.fixup.alternate.enabled to false turned of DNS caching. None of these things worked, but migrating all my /etc/hosts config from multiple domains on a single line to separate lines did. Hope this helps someone.