OS X DNS cache reset script

In 10.10 Apple replaced the then 12-year-old mDNSResponder, which does DNS (apart from other things) with &quot;discoveryd&quot;, which had issues so they reverted the change.<p><a href="http:&#x2F;&#x2F;arstechnica.com&#x2F;apple&#x2F;2015&#x2F;01&#x2F;why-dns-in-os-x-10-10-is-broken-and-what-you-can-do-to-fix-it&#x2F;" rel="nofollow">http:&#x2F;&#x2F;arstechnica.com&#x2F;apple&#x2F;2015&#x2F;01&#x2F;why-dns-in-os-x-10-10-i...</a><p><a href="http:&#x2F;&#x2F;arstechnica.com&#x2F;apple&#x2F;2015&#x2F;05&#x2F;new-os-x-beta-dumps-discoveryd-restores-mdnsresponder-to-fix-dns-bugs&#x2F;" rel="nofollow">http:&#x2F;&#x2F;arstechnica.com&#x2F;apple&#x2F;2015&#x2F;05&#x2F;new-os-x-beta-dumps-dis...</a><p><a href="https:&#x2F;&#x2F;support.apple.com&#x2F;en-us&#x2F;HT202516" rel="nofollow">https:&#x2F;&#x2F;support.apple.com&#x2F;en-us&#x2F;HT202516</a>

What a worthless link. How about an explanation of the problem? Stop what? Not resetting? Why is a reset necessary? And why the double-negative? Why not &quot;noreallyjustfuckingresetitalready&quot;?

Too bad they didn&#x27;t address the DNS problem in the Keynote. This is a bit of an exaggeration, but I do feel I&#x27;ve spun mDNSResponder more often than using their Messages app.<p>That&#x27;s not a positive feeling. Especially if you&#x27;re with a client and your browser stops resolving and your client is watching you open up terminal to spin mDNSResponder

Could someone add some context please? I see that apparently the method to flush the DNS cache changes between versions. Is there a deeper reason why this is necessary?

What&#x27;s the context of this?

I&#x27;d just do<p><pre><code> dscacheutil -flushcache || \ discoveryutil mdnsflushcache || \ killall -HUP mDNSResponder</code></pre>

Could OSX just have a way to disable negative caching completely? All it does is troll me when I&#x27;m on bad wifi and the DNS lookup for www.google.com gets dropped and that negative response is cached. Can we just stop doing that?<p>I can&#x27;t recall the last time I had a positive cache entry issue, but the last time the dropped DNS lookup for www.google.com happened to me was like 2 days ago...

Actually, this should be included with the Mavericks+ version<p><pre><code> sudo discoveryutil udnsflushcaches</code></pre>

This is quite nice (I went with an alias myself). Does anyone know if it changed again in macOS?

Also, just think about how we get all new browser user agents because of this.

It&#x27;s good practice to include<p><pre><code> set -eu set -o pipefail </code></pre> to avoid the default ON ERROR RESUME NEXT behaviour of bash.

I have in my .bash_profile for this purpose: alias cleardns=&#x27;dscacheutil -flushcache&#x27; but this solution is way funnier.

&gt;(or whatever your name is)<p>Why is changing names seen as a negative thing? My company also changed its name a month ago, and several customers leaving negative feedback said included this phrase or something similar, while to my recollection none of the positive feedback (which we have way more of) took mention of the name change.

<p><pre><code> echo &quot;¯\_(ツ)_&#x2F;¯&quot; </code></pre> Something about seeing the shrug emoji in code just cracks me up every time.

Someone renamed this. Why?