<div dir="ltr">I believe it is related to the Lets Encrypt root cert that expired overnight.<div><br></div><div>I've seen quite a few older devices today having issues accessing sites using lets encrypt certs. <br><div><br></div><div>More info on the issue can be found here: <a href="https://docs.certifytheweb.com/docs/kb/kb-202109-letsencrypt/">https://docs.certifytheweb.com/docs/kb/kb-202109-letsencrypt/</a></div></div></div><br><div class="gmail_quote"><div dir="ltr" class="gmail_attr">On Fri, Oct 1, 2021 at 12:36 PM Mark Andrews <<a href="mailto:marka@isc.org">marka@isc.org</a>> wrote:<br></div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex">More correctly they had working DNSSEC deployed (<a href="https://dnsviz.net/d/slack.com/YVXX_g/dnssec/" rel="noreferrer" target="_blank">https://dnsviz.net/d/slack.com/YVXX_g/dnssec/</a>) and then pulled both the DS records for <a href="http://slack.com" rel="noreferrer" target="_blank">slack.com</a> and the DNSSEC records in <a href="http://slack.com" rel="noreferrer" target="_blank">slack.com</a> AT THE SAME TIME resulting in DNSSEC validation failures. Cached DS records said <a href="http://slack.com" rel="noreferrer" target="_blank">slack.com</a> is signed but the answers from the <a href="http://slack.com" rel="noreferrer" target="_blank">slack.com</a> servers where missing the DNSSEC records. They failed to wait for the DS records to expire from DNS caches before removing the DNSSEC records in <a href="http://slack.com" rel="noreferrer" target="_blank">slack.com</a>. Failure to wait for unsigned responses to clear caches before publishing DS records can also cause issues with multiple levels of caching.<br>
<br>
> On 1 Oct 2021, at 08:23, Scott Howard <<a href="mailto:scott@doc.net.au" target="_blank">scott@doc.net.au</a>> wrote:<br>
> <br>
> They broke (and subsequently fixed) their DNSSEC configuration many hours ago, but it was broken long enough to get cached by some servers for up to 24 hours so some users are still having issues connecting.<br>
> <br>
> Short of the classic "have your ISP clear their DNS cache" not much anyone can do except wait it out...<br>
> <br>
> <a href="https://status.slack.com/2021-09/06c1e17de93e7dc2" rel="noreferrer" target="_blank">https://status.slack.com/2021-09/06c1e17de93e7dc2</a><br>
> <br>
> Scott<br>
> <br>
> <br>
> On Thu, Sep 30, 2021 at 3:19 PM Andrew Yager <<a href="mailto:andrew@rwts.com.au" target="_blank">andrew@rwts.com.au</a>> wrote:<br>
> Hi,<br>
> <br>
> Slack is down and finding a few other (non slack) services etc being broken seemingly with DNS things. Anyone know what’s going on?<br>
> <br>
> A<br>
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-- <br>
Mark Andrews, ISC<br>
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