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<div dir="auto">Seems to me RFC2181 already answered this years ago. </div><div id="aqm-signature" dir="auto" style="color: black;"><div dir="auto">-- </div><div dir="auto">Andrew Sullivan</div><div dir="auto">Please excuse my clumbsy thums.</div></div><div dir='auto'><br></div>
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<p style="color: black; font-size: 10pt; font-family: sans-serif; margin: 8pt 0;">On January 18, 2019 17:21:40 Greg Choules <gregchoules@googlemail.com> wrote:</p>
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<div dir="ltr">Hi Fred.<div>No, I am not talking about dscacheutil or any particular client software. I just want to know whether, in the opinion of the world's DNS professionals, recursive servers should or shouldn't ever send answers from cache with TTL=0.</div><div><br></div><div>cheers, Greg</div></div><br><div class="gmail_quote"><div dir="ltr">On Thu, 17 Jan 2019 at 23:15, m3047 <<a href="mailto:m3047@m3047.net">m3047@m3047.net</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">Who cares about the RFC? In practice, SOME caching resolvers (and that's <br>
being charitable) WILL answer with TTL=0. I've had to live with PFSense <br>
deployments which did this.<br>
<br>
Which in turn leads to things like (for Mac users):<br>
<br>
dscacheutil -flushcache<br>
<br>
Is that what you're talking about?<br>
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On Thu, 17 Jan 2019, Greg Choules wrote:<br>
> [...]<br>
><br>
> Is there ever a case, for cached answers, that the recursive server would<br>
> answer the client with TTL=0? Or would that be illegal? RFC1034 states that<br>
> records with TTL=0 "should not be cached". Note "should" and not "must".<br>
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