<p>We have a kubernetes cluster deployed on AWS EKS, and are experiencing intermittent timeouts on CoreDNS pods, usually clustered in groups of 5-15 failed queries in span of around 5 minutes. In a cluster, all queries regard the same hostname.</p>
<p>CoreDNS spits such logs:</p>
<pre><code>[ERROR] plugin/errors: 2 example.com. A: read udp [coreDNSpodIP]:39068-&gt;172.16.0.2:53: i/o timeout
</code></pre>
<p>The cluster is deployed in a VPC with CIDR of <code>172.16.0.0/16</code>, tho I cant determine what's under <code>172.15.0.2</code></p>
<p>They appear from time to time, we cannot reproduce the event that triggers them, nor correlate to any event on cluster. The coreDNS pods are working normally and at the same time are serving other queries well. What may be the cause and solution to fix the behavior?</p>

<p>You may be hitting a limit after which all requests are throttled.</p>
<p>There are 2 things that come to mind</p>
<ul>
<li><a href="https://coredns.io/plugins/cache/" rel="nofollow noreferrer">Enable DNS caching on CoreDNS</a></li>
<li><a href="https://aws.amazon.com/premiumsupport/knowledge-center/dns-resolution-failures-ec2-linux/" rel="nofollow noreferrer">Check for EC2 throttling issues</a></li>
</ul>
