<div dir="ltr"><br><div class="gmail_extra"><br><div class="gmail_quote">On Thu, Sep 8, 2016 at 2:59 PM, Jeremy Rowley <span dir="ltr"><<a href="mailto:jeremy.rowley@digicert.com" target="_blank">jeremy.rowley@digicert.com</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">I suppose that would work for us but wouldn't there be the same concern with _pki and wildcard domains.</blockquote><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
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Why not permit both validation methods?<br></blockquote><div><br></div><div>Because a Wildcard DNS is statistically unlikely to be CNAME'd to <random token>.anything, while Wildcard DNS implies a significantly greater probability that <random>.anything will CNAME to <fixed string></div><div><br></div><div>The former - using _pki.[something] to CNAME to <random>.[something] - is robust in the presence of Wildcard DNS, and still ensures the critical property desired by <random> - that it's unlikely to happen except through a demonstration of control.</div></div></div></div>