<html><head>
<meta content="text/html; charset=UTF-8" http-equiv="Content-Type">
</head><body bgcolor="#FFFFFF" text="#000000"><br>
<br>
<blockquote style="border: 0px none;"
cite="mid:alpine.LSU.2.00.1411301422460.10999@hermes-1.csi.cam.ac.uk"
type="cite">
<div style="margin:30px 25px 10px 25px;" class="__pbConvHr"><div
style="display:table;width:100%;border-top:1px solid
#EDEEF0;padding-top:5px"> <div
style="display:table-cell;vertical-align:middle;padding-right:6px;"><img
photoaddress="dot@dotat.at" photoname="Tony Finch"
src="cid:part1.06030001.03070806@redbarn.org"
name="compose-unknown-contact.jpg" height="25px" width="25px"></div> <div
style="display:table-cell;white-space:nowrap;vertical-align:middle;width:100%">
<a moz-do-not-send="true" href="mailto:dot@dotat.at"
style="color:#737F92
!important;padding-right:6px;font-weight:bold;text-decoration:none
!important;">Tony Finch</a></div> <div
style="display:table-cell;white-space:nowrap;vertical-align:middle;">
<font color="#9FA2A5"><span style="padding-left:6px">Sunday, November
30, 2014 6:26 AM</span></font></div></div></div>
<div style="color:#888888;margin-left:24px;margin-right:24px;"
__pbrmquotes="true" class="__pbConvBody"><div><!----><br>You can do that
with the current DNS protocol: just send all the queries<br>and wait
for all the replies. (This is particularly easy over TCP.)<br>There's no
need for more than one round trip in most cases, or maybe two<br>if the
answer involves CNAME/MX/SRV etc.<br>
</div></div>
</blockquote>
so, you're willing to send a query for every ancestor domain, even the
ones that turn out not to be zone cuts. you're also willing to transmit
microburst UDP, or to depend on RDNS servers having effectively
unlimited TCB capacity. <span>i am not hip to any of that. </span>see
also:<br>
<br>
<a class="moz-txt-link-freetext" href="https://tools.ietf.org/html/draft-ietf-dnsop-edns-chain-query-01">https://tools.ietf.org/html/draft-ietf-dnsop-edns-chain-query-01</a><br>
<br>
<div class="moz-signature">-- <br>Paul Vixie<br>
</div>
</body></html>