macOS – Updating OSX Mavericks to Recognize DNS Change in ‘/etc/hosts’

dnsmacos

A common way to "block" a website (eg, to eliminate it as a distraction) is to edit /etc/hosts and point the domain to the loopback address. Eg:

# Stop goofing off
127.0.0.1 youtube.com

On Mavericks, I find that changes like this are seemingly ignored by the OS; after editing the file (with sudo) and saving, the site that should be blocked still loads.

I've tried resetting my DNS cache as follows:

dscacheutil -flushcache
sudo killall -HUP mDNSResponder

But the site still loads.

How can I get OSX Mavericks to notice a change to /etc/hosts?

Best Answer

According to the the hosts(5) manual page, the /etc/hosts file is used by mDNSResponder. Your attempts are correctly flushing the computer wide cache but you also need to flush the browser's private cache.

After each edit of /etc/hosts reset the mDNSResponder cache using this Apple technical note, OS X: How to reset the DNS cache:

sudo dscacheutil -flushcache

After doing this, reset your browser caches:

  • Safari: use the menu item Safari > Reset Safari.
  • Chrome: use the menu item Chrome > Clear Browsing Data.
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